Antistatic ultrafine fiber and method for producing the same

ABSTRACT

According to the present invention, there are provided a polyester ultrafine fiber excellent in durability and having an antistatic property, and a method for producing the same. Further, there are provided an antistatic polyester ultrafine fiber capable of being imparted with various functions such as ultraviolet blocking effect, cation dyeability, flame retardancy, spun-like bulkiness, soft touch and resilience of the surface, reboundability, dryness, naturalness, and spunize appearance, wool-like touch feel, wrinkle recoverability, and water absorbing/quick drying property, by introduction of a third component into the antistatic polyester ultrafine fiber, combination with other fibers, change in cross sectional shape, and the like, and a method for producing the same.

TECHNICAL FIELD

The present invention relates to a polyester ultrafine fiber excellent in durability and having an antistatic property, and a method for producing the same. More particularly, it relates to an antistatic polyester ultrafine fiber capable of being imparted with various functions such as ultraviolet blocking effect, cation dyeability, flame retardancy, spun-like bulkiness, soft touch and resilience of the surface, reboundability, dryness, naturalness, and spunize appearance, wool-like touch feel, wrinkle recoverability, and water absorbing/quick drying property by introduction of a third component, combination with other fibers, change in cross sectional shape, and the like, and a method for producing the same.

BACKGROUND ART

Conventionally, there has been made an attempt to impart hydrophilicity to a polyester for expression of an antistatic property. Up to now, a large number of proposals have been made. For example, there are known a method in which to a polyester, a polyoxyalkylene type polyether compound is added (JP-B-39-5214); a method in which to a polyester, a substantially non-compatible polyoxyalkylene type polyether compound and an organic/inorganic ionic compound are added (JP-B-44-31828, JP-B-60-11944, JP-A-53-80497, JP-A-53-149247, JP-A-60-39413, JP-A-3-139556, and the like). In these methods, in actuality, the resulting fiber has an antistatic property when it has a single yarn fineness of more than 1.6 dtex. However, none has an antistatic property due to variations in core/sheath formation, or variations in single yarn fineness for an ultrafine yarn.

However, in recent years, there have been more and more increasing demands for texture, touch, appearance, and the like for woven and knitted fabrics. Thus, a cloth resulting from knitting or weaving using a conventional ultrafine polyester drawn yarn provides a soft texture, and is also improved in performances such as heat retaining property, and water absorbing or moisture absorbing property. However, the improvement was not sufficient enough to say that the number of clothes having an antistatic property of inhibiting crackling static electricity is equal to nil. Particularly, in actuality, a cloth having an antistatic property has not been obtained in the application of blocking ultraviolet rays and suppressing static electricity for outdoor sport clothes, uniforms, and the like.

Further, polyester cannot be said to be favorable in dyeability as a fiber for clothes, and has a defect of poor clarity of a dyed product thereof. Conventionally, in order to compensate for such a defect, there is known a basic dye-dyeable polyester including a sulfonic acid base-containing component typified by 5-sodium sulfoisophthalic acid or the like, copolymerized therein (which will be hereinafter abbreviated as a cation dyeable polyester). A fiber including such a polyester is used in the field of clothes.

However, these cation dyeable polyester fibers are higher in melt viscosity than a general polyester fiber, and hence are less likely to undergo melt dropping during burning. For this reason, they have a defect of being susceptible to spread of a fire, and hence they are unfavorably restricted in use in the field requiring flame retardancy.

In order to resolve such problems, there are proposed: in JP-A-7-109621, a polyester containing a specific phosphorus-containing dicarboxylic acid compound copolymerized therein in addition to a sulfonic acid base-containing component; and in JP-A-2005-273043, a polyester containing a specific organic phosphorus compound copolymerized therein.

However, with the methods, by the acid catalyst action of the phosphorus compound, formation of diethylene glycol is promoted in the polymerization reaction process. This results in a high diethylene glycol content, which unfavorably degrades the spinnability and the light resistance.

Further, for a polyester fiber, particularly, for a polyester filament yarn, as methods for imparting a spun-like texture as with high-grade wool and bulkiness, as shown in, for example, JP-B-60-11130, JP-B-61-19733, JP-A-8-13275, and JP-A-2006-169697, the following methods are proposed: the bulkiness is improved by a spun-like false twisted two layer structure yarn including polyester filament yarns having two or more elongation differences in combination; or a spontaneously elongatable polyester multifilament yarn and a heat shrinkable polyester multifilament yarn are combined by an air jet nozzle; or while performing a relaxation heat treatment on a polyester multifilament yarn which becomes spontaneously elongatable by undergoing a relaxation heat treatment, a heat shrinkable polyester multifilament yarn is continuously fed to the spontaneously elongatable polyester multifilament yarn after the relaxing heat treatment for combination by an air jet nozzle (e.g., JP-A-1-250425).

However, for a general drawn yarn (FOY), even if the yarn has an antistatic property, fluffing becomes more likely to occur due to twisting deformation or friction when the foregoing false twisting or air combination is performed. For this reason, in actuality, it was not possible to impart a sufficient antistatic property thereto.

RELATED ART DOCUMENTS Patent Documents

-   Patent Document 1: JP-B-39-5214 -   Patent Document 2: JP-B-44-31828 -   Patent Document 3: JP-B-60-11944 -   Patent Document 4: JP-A-53-80497 -   Patent Document 5: JP-A-60-39413 -   Patent Document 6: JP-A-3-139556 -   Patent Document 7: JP-A-7-109621 -   Patent Document 8: JP-A-2005-273043 -   Patent Document 9: JP-B-60-11130 -   Patent Document 10: JP-B-61-19733 -   Patent Document 11: JP-A-8-13275 -   Patent Document 12: JP-A-2006-169697

DISCLOSURE OF THE INVENTION Problems that the Invention is to Solve

It is an object of the present invention to provide a polyester ultrafine fiber which solves the problems which the related art technology has, and is excellent in durability and has an antistatic property, and a method for producing the same.

Further, it is another object of the invention to provide an antistatic polyester ultrafine fiber capable of being imparted with various functions such as ultraviolet blocking effect, cation dyeability, flame retardancy, spun-like bulkiness, soft touch and resilience of the surface, reboundability, dryness, naturalness, and spunize appearance, wool-like touch feel, wrinkle recoverability, and water absorbing/quick drying property, by introduction of a third component into the antistatic polyester ultrafine fiber, combination with other fibers, change in cross sectional shape, and the like, and a method for producing the same.

Means for Solving the Problems

Namely, in accordance with the present invention,

(1) there is provided an antistatic core sheath type polyester ultrafine fiber, which is a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a copolymerized polyester B, and is characterized by satisfying the following requirements:

(i) the single yarn fineness being 1.5 dtex or less;

(ii) the ratio A:B of the area A of the core part and the area B of the sheath part being within the range of 5:95 to 80:20;

(iii) the single yarn strength being 3.0 cN/dtex or more;

(iv) the friction-charged voltage of the yarn being 2000 V or less; and

(v) the polyester A being an antistatic polyester including, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester;

R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1)

[where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]

Herein, the copolymerized polyester B is preferably:

a polyester including an organic type ultraviolet absorbing component copolymerized therein in an amount of 0.1 to 5.0 wt % based on the total weight of the polyester;

a polyester including an organic sulfonic acid metal salt copolymerized therein in an amount of 1.0 to 5.0 mol % based on the total amount of acid components except for the organic sulfonic acid metal salt;

or

a polyester including a phosphorus type flame retardant component represented by the following general formula (2) in an amount of 1,000 to 10,000 ppm in terms of phosphorus atom based on the total weight of the polyester:

[where in the formula, R₁ is hydrogen or a hydroxyalkyl group having 1 to 10 carbon atoms, R₂ is hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 24 carbon atoms, and R₃ is hydrogen, an alkyl group or a hydroxyalkyl group having 1 to 10 carbon atoms.]

Further, it is preferable that the antistatic core sheath type polyester ultrafine fiber has 3 to 8 fin parts in a shape protruding outwardly from the fiber cross section central part in a cross section orthogonal to the direction of length of the single yarn, or has a flat shape including 3 to 6 round cross section single yarns bonded to one another in the longitudinal direction in a cross section orthogonal to the direction of length of the single yarn.

Still further, in accordance with the present invention, the following are provided:

(2) An antistatic polyester composite false twisted textured yarn includes: two kinds of polyester filament yarns different in elongation, including bundled portions each including an alternately twisted yarn-like wrapped portion and an entangled portion, and open portions, alternately formed in the longitudinal direction therein, and is characterized by satisfying the following requirements (i) to (iv):

(i) the polyester filament yarn X having a smaller elongation being a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a copolymerized polyester B, the polyester A including an antistatic polyester including, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester;

(ii) the polyester filament yarn Y having a larger elongation including a polyester containing a matting agent in an amount of 0 to 10 wt % per 100 parts by weight of an aromatic polyester;

(iii) being in a two-layer structure in which the polyester filament yarn X forms a core part of the composite false twisted yarn, and the polyester filament yarn Y wraps around the core part in an alternately twisted yarn form to form an outer layer part (sheath part); and

(iv) the mean yarn length of the polyester filament yarn Y being larger than the mean yarn length of the polyester filament yarn X by 5 to 20%,

R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1)

[where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.];

(3) An antistatic polyester combined filament yarn includes an antistatic polyester filament yarn X and a polyester filament yarn Y, and is characterized by satisfying the following conditions (i) to (vi):

(i) the antistatic polyester filament yarn X being a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a copolymerized polyester B, the polyester A including an antistatic polyester containing, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester;

(ii) the single yarn fineness of the polyester filament yarn X being 1.5 dtex or less;

(iii) the friction-charged voltage of the combined filament yarn being 2000 V or less;

(iv) the combined filament yarn being the one obtained through an air entanglement step and a relaxation heat treatment step in this order;

(v) the combining ratio of the polyester filament yarn X and the polyester filament yarn Y being 8:2 to 6:4; and

(vi) the polyester filament yarn X forming an outer layer part of the combined filament yarn, and the polyester filament yarn Y forming an inner layer part thereof,

R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1)

[where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]; and

(4) A method for producing an antistatic polyester combined filament yarn, is characterized by: subjecting, an antistatic polyester filament yarn X′ having an elongation (ELA) of 80% or more, an elastic recovery at 10% elongation (ERA) of 50% or less, an elongation shear modulus (EMA) of 5.89 GPa or less, a crystallinity (XpA) of 25% or more, a boiling water shrinkage (BWSA) of 3% or less, and a thermal stress at 160° C. (TSA) of 0.44 mN/dtex or less, and satisfying the requirements of the following (i) and the like, to a relaxation heat treatment; then, merging it with a polyester filament yarn Y′ having an elongation (ELB) of 40% or less, an elongation shear modulus (EMB) of 7.85 GPa or more, a boiling water shrinkage (BWSB) of 5% or more, and a thermal stress at 160° C. (TSB) of 0.88 mN/dtex or more such that the weight ratio of the polyester multifilament yarn X′ and the polyester multifilament yarn Y′ is 45/55 to 70/30, and then, performing an entanglement treatment:

(i) the antistatic polyester multifilament yarn X′ being a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a copolymerized polyester B, the polyester A including an antistatic polyester containing, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester; and

(ii) the single yarn fineness of the polyester multifilament yarn X′ being 1.5 dtex or less;

R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1)

[where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]

Advantage of the Invention

In accordance with the present invention, there are provided a polyester ultrafine fiber excellent in durability and having an antistatic property, and a method for producing the same.

Further, according to the present invention, there are provided an antistatic polyester ultrafine fiber capable of being imparted with various functions such as ultraviolet blocking effect, cation dyeability, flame retardancy, spun-like bulkiness, soft touch and resilience of the surface, reboundability, dryness, naturalness, and spunize appearance, wool-like touch feel, wrinkle recoverability, and water absorbing/quick drying property, by introduction of a third component into the antistatic polyester ultrafine fiber, combination with other fibers, change in cross sectional shape, and the like, and a method for producing the same.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A schematic view showing one example of a false twisting apparatus for use in the present invention;

FIGS. 2A and 2B Schematic views each showing one example of a yarn structure of an antistatic polyester composite false twisted textured yarn of the invention;

FIG. 3 A schematic view showing one example of a fiber combining apparatus for use in production of an antistatic polyester combined filament yarn of the invention;

FIG. 4 A perspective view showing the outline of a wrinkle recovering measuring apparatus of a cloth containing the antistatic polyester combined filament yarn of the invention;

FIG. 5 A schematic view showing one example of a cross section of an antistatic core sheath type polyester ultrafine fiber of the invention;

FIG. 6 A schematic view showing one example of a spinneret discharge port for use in spinning the antistatic core sheath type polyester ultrafine fiber of FIG. 5;

FIGS. 7A to 7H Schematic views each showing one example of across section of a flat cross section fiber of the invention; and

FIG. 8 A schematic view showing one example of a flat shaped cross section including 3 to 6 round cross section single yarns bonded to one another in the longitudinal direction of the invention.

REFERENCE NUMERALS AND SIGNS OF THE DRAWINGS

In FIG. 1, 3 and 3′ denote two yarns having mutually different elongations; 4, a guide; 5, a tension adjusting device; 6, a feed roller; 7, an air jet nozzle for entanglement; 8, a first delivery roller; 9, a heater; 10, a false twister; 11, a second delivery roller; and 13, a cheese.

In FIGS. 2A and 2B, I denotes an alternately twisted yarn-like wrapped portion; II, an entangled portion; and III, an open portion.

In FIG. 3, X′ denotes a polyester filament yarn which spontaneously elongates by undergoing a relaxation heat treatment; Y′, a polyester filament yarn; 1, a feed roller; 2, a first take-up roll (heat roll); 3, an interlace nozzle; 4, a second take-up roll; 5, a non-contact heater; and 6, a package.

In FIG. 5, a1 denotes the length between the inscribed circle center of the fiber cross section inner surface wall and the top of the fin part; and b1, the radius of the inscribed circle (core part extrapolation inscribed circle) of the fiber cross section inner surface wall.

In FIG. 6, a2 denotes the radius of the core part forming circular discharge port; and b2, the length between the central point of the circular discharge port and the tip end of the fin part forming discharge port.

In FIG. 8, A denotes the maximum value of the length of the long side; B, the maximum value of the length of the short side; and C, the minimum value of the length of the short side.

BEST MODE FOR CARRYING OUT THE INVENTION

Below, an embodiment of a first invention of the present application will be described in details.

The first invention of the present application is an antistatic core sheath type polyester ultrafine fiber, being a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a copolymerized polyester B, characterized by satisfying the following requirements:

(i) the single yarn fineness being 1.5 dtex or less;

(ii) the ratio A:B of the area A of the core part and the area B of the sheath part being within the range of 5:95 to 80:20;

(iii) the single yarn strength being 3.0 cN/dtex or more;

(iv) the friction-charged voltage of the yarn being 2000 V or less; and

(v) the polyester A being an antistatic polyester including, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester;

R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1)

[where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]

The polyester used in the invention embraces a polymer or a copolymer resulting from polycondensation of dicarboxylic acid or an ester forming derivative thereof, and one or more selected from a diol or an ester forming derivative thereof, hydroxycarboxylic acid or an ester forming derivative, and lactone. An aromatic polyester having an aromatic ring as the chain unit of the polymer is preferably exemplified.

As the bifunctional aromatic carboxylic acids herein used, mention may be made of terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, 3,3′-biphenyldicarboxylic acid, 4,4′-biphenylether dicarboxylic acid, 4,4′-biphenylmethanedicarboxylic acid, 4,4′-biphenylsulfonedicarboxylic acid, 4,4′-biphenylisopropylidenedicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4′-dicarboxylic acid, 2,5-anthracenedicarboxylic acid, 2,6-anthracenedicarboxylic acid, 4,4′-p-phenylenedicarboxylic acid, 2,5-pyridinedicarboxylic acid, β-hydroxyethoxybenzoic acid, p-oxybenzoic acid, and the like. Particularly, terephthalic acid is preferred.

These bifunctional aromatic carboxylic acids may be used in combination of two or more thereof. Incidentally, if in small amounts, with these bifunctional aromatic carboxylic acids, bifunctional aliphatic carboxylic acids such as adipic acid, azelaic acid, sebacic acid, and dodecadionic acid, and a bifunctional alicyclic carboxylic acid such as cyclohexane dicarboxylic acid, and 5-sodium sulfoisophthalic acid, and the like can be used in combination of two or more thereof.

Whereas, as the diol compounds, mention may be preferably made of aliphatic diols such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 2-methyl-1,3-propanediol, diethylene glycol, and trimethylene glycol, and alicyclic diols such as 1,4-cyclohexanedimethanol, and mixtures thereof. Further, if in a small amount, with the diol compounds, polyoxyalkylene glycol unblocked at both terminals or at one terminal can be copolymerized.

Further, polycarboxylic acids such as trimellitic acid and pyromellitic acid, and polyols such as glycerine, trimethylolpropane, and pentaerithritol can be used in an amount in such a range that polyester is substantially linear.

Whereas, as the hydroxycarboxylic acids, mention may be made of glycolic acid, lactic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and ester forming derivatives thereof, and the like. As the lactones, mention may be made of caprolactone, valerolactone, propiolactone, undecalactone, 1,5-oxepan-2-one, and the like.

As specific preferable aromatic polyesters, mention may be made of polyethylene terephthalate, polybutylene terephthalate, polyhexylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene-1,2-bis(phenoxy)ethane-4,4′-dicarboxylate, and the like, and in addition, copolymerized polyesters such as polyethylene isophthalate/terephthalate, polybutylene terephthalate/isophthalate, and polybutylene terephthalate/decane dicarboxylate. Out of these, particularly preferred are polyethylene terephthalate and polybutylene terephthalate balanced in mechanical properties, formability, and the like.

As the aliphatic polyester resins, there are exemplified polymers containing aliphatic hydroxycarboxylic acid as a main constituent component, polymers resulting from polycondensation of an aliphatic polyvalent carboxylic acid or an ester forming derivative, and an aliphatic polyhydric alcohol as main components, or copolymers thereof.

As the polymers containing an aliphatic hydroxycarboxylic acid as a main constituent component, there can be exemplified polycondensates of glycolic acid, lactic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, and the like, or copolymers thereof. Out of these, mention may be made of polyglycolic acid, polylactic acid, poly 3-hydroxycarboxylbutyric acid, poly 4-polyhydroxybutyric acid, poly 3-hydroxyhexanoic acid, or polycaprolactone, and copolymers thereof, and the like. Particularly, preferable use can be made of poly L-lactic acid, poly D-lactic acid, and stereocomplex polylactic acid forming a stereocomplex crystal, and racemic polylactic acid.

As polylactic acids, there may be used the ones containing L-lactic acid and/or D-lactic acid as a main repeating unit. However, particularly, those with a melting point of 150° C. or more are preferable (herein, the term “main” is intended to mean that the component accounts for 50% or more of the total amount). In the case where the melting point is lower than 150° C., when the material is formed in a fiber, poor drawability is caused due to occurrence of fusion between single yarns, or melting defects occur during dyeing processing, during heat setting, and during friction heating, or other defects occur. Thus, these result in a remarkably low quality of the products thereof. This is undesirable for use in clothes application.

Preferably, polylactic acid has a melting point of 170° C. or more, and further preferably, the melting point is 200° C. or more. Herein, the melting point means the peak temperature of the melting peak obtained by DSC measurement. Particularly, in order to impart the heat resistance, it is preferable that polylactic acid forms a stereocomplex crystal.

Herein, the stereocomplex polylactic acid is an eutectic formed by the poly L lactic segment and the poly D lactic segment.

The stereocomplex crystal generally has a higher melting point than that of the crystal formed by poly L lactic acid or poly D lactic acid alone. Therefore, it can be expected that even a slight content thereof produces an effect of enhancing the heat resistance. Particularly, the effect is remarkably exerted when the amount of the stereocomplex crystal based on the total crystal amount is large. The stereocomplex crystallinity (S) according to the following equation is preferably 95% or more, and further preferably 100%.

S=[ΔHms/(ΔHmh+ΔHms)]×100

(where ΔHms is the fusion enthalpy of the stereocomplex phase crystal, and ΔHmh is the fusion enthalpy of the homogeneous phase polylactic crystal.)

The aromatic polyester is synthesized by a given method. For example, polyethylene terephthalate will be described as follows. Terephthalic acid and ethylene glycol are allowed to directly undergo an esterification reaction. Alternatively, a lower alkyl ester of terephthalic acid such as dimethyl terephthalate and ethylene glycol are allowed to undergo a transesterification reaction, or terephthalic acid and ethylene oxide are allowed to react with each other. As a result, glycol ester of terephthalic acid and/or a lower polymer thereof is formed. By such a first stage reaction, and then, a second stage reaction in which the product is heated under reduced pressure, and thereby undergoes a polycondensation reaction until a desired polymerization degree is reached, easy production is accomplished.

In the invention, the polyoxyalkylene type polyether (a) to be added to the polyester A at the core part may be polyoxyalkylene glycol including a single oxyalkylene unit or a copolymerized polyoxyalkylene glycol including two or more oxyalkylene units so long as it is substantially insoluble in a polyester. Alternatively, it may be a polyoxyethylene type polyether represented by the following general formula (I):

R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1)

[where R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]

Specific examples of such a polyoxyalkylene type polyether may include polyoxyethylene glycol having a molecular weight of 4000 or more, polyoxypropylene glycol and polyoxytetramethylene glycol having a molecular weight of 1000 or more, ethylene oxide or propylene oxide copolymer having a molecular weight of 2000 or more, trimethylolpropane ethylene oxide adduct having a molecular weight of 4000 or more, nonylphenol ethylene oxide adduct having a molecular weight of 3000 or more, and compounds obtained by adding substituted ethylene oxide having 6 or more carbon atoms to the terminal OH groups thereof. Out of these, preferred are polyoxyethylene glycol having a molecular weight of 10000 to 100000, and compounds obtained by adding C₈₋₄₀-alkyl group-substituted ethylene oxide to both the terminals of polyoxyethylene glycol, having a molecular weight of 5000 to 16000.

The amount of such a polyoxyalkylene type polyether compound to be added is within the range of 0.2 to 30 parts by weight per 100 parts by weight of the aromatic polyester. When the amount is less than 0.2 part by weight, the hydrophilicity is insufficient, and a sufficient antistatic property cannot be exhibited. On the other hand, even when the amount is set larger than 30 parts by weight, the antistatic property improving effect cannot be observed any longer, and on the contrary, the mechanical properties of the resulting composition are impaired. Further, the polyether becomes more likely to bleed out, and hence the biting property to a ruder of a chip during melt forming is reduced, and the forming stability is also deteriorated.

In the invention, in order to particularly improve the antistatic property of the polyester A, an organic ionic compound is added. As the organic ionic compounds, for example, mention may be made of sulfonic acid metal salts and sulfonic acid quaternary phosphonium salts represented by the following general formulae (II) and (III):

RSO₃N  (II)

(where in the formula, R denotes an alkyl group having 3 to 30 carbon atoms or an aryl group having 7 to 40 carbon atoms, and M denotes an alkali metal or an alkaline-earth metal.

RSO₃PR₁R₂R₃R₄  (III)

(where in the formula, R is an alkyl group having 3 to 30 carbon atoms or an aryl group having 7 to 40 carbon atoms, and R₁, R₂, R₃, and R₄ are alkyl groups or aryl groups, and, out of these, preferably lower alkyl groups, phenyl groups, or benzyl groups.)

In the formula (II), when R is an alkyl group, the alkyl group may be straight chain or may have a branched side chain. M is an alkali metal such as Na, K, or Li, or an alkaline-earth metal such as Mg or Ca, and, out of these, Li, Na, or K is preferred. Such sulfonic acid metal salts may be used singly alone, or may be used in mixture of two or more thereof. Preferred specific examples thereof may include sodium stearyl sulfonate, sodium octyl sulfonate, sodium dodecyl sulfonate, a sodium alkyl sulfonate mixture having 14 carbon atoms on the average, a sodium dodecyl benzene sulfonate mixture, sodium dodecyl benzene sulfonate (hard type or soft type), lithium dodecyl benzene sulfonate (hard type or soft type), and magnesium dodecyl benzene sulfonate (hard type or soft type).

Further, the sulfonic acid quaternary phosphonium salts in the formula (III) may be used singly alone or may be used in mixture of two or more thereof. Preferred specific examples thereof may include tetrabutylphosphonium alkyl sulfonate having 14 carbon atoms on the average, tetraphenyl phosphonium alkyl sulfonate having 14 carbon atoms on the average, butyl triphenyl phosphonium alkyl sulfonate having 14 carbon atoms on the average, tetrabutylphosphonium dodecyl benzene sulfonate (hard type or soft type), tetraphenyl phosphonium dodecyl benzene sulfonate (hard type or soft type), and benzyl triphenyl phosphonium dodecyl benzene sulfonate (hard type or soft type).

Such organic ionic compounds may be used alone, or in combination of two or more thereof. The amount thereof is preferably within the range of 0.05 to 10 parts by weight per 100 parts by weight of the aromatic polyester. When the amount is less than 0.05 part by weight, the effect of improving the antistatic property is small. Whereas, when the amount exceeds parts by weight, the mechanical properties of the composition are impaired. Further, the ionic compound also becomes more likely to bleed out, and hence the biting property to a ruder of a chip during melt forming is reduced, and the forming stability is also deteriorated.

In the invention, in order to impart various functions to the fiber, the polyester B at the sheath part is configured to be a copolymerized polyester. Herein, the term “copolymerized” embraces the one in which a third component is incorporated into the polymer skeleton by a general polymerization reaction, and in addition, a polymerization form referred to as a so-called chain extender in which a third component is blended with a polymer, followed by reaction with the terminal group, to be incorporated into the polymer skeleton, and even a polymerization form in which a third component is incorporated into the polymer skeleton by a redistribution reaction.

First, in the invention, in order to improve the weather resistance, in the polyester B, an organic type ultraviolet absorber is contained and copolymerized in an amount of 0.1 to 5.0 wt % (preferably 0.5 to 3.0 wt %) based on the total weight of the polyester. When the content of the organic type ultraviolet absorber is less than 0.1 wt %, a sufficient ultraviolet absorbing performance cannot be obtained, and hence such a content is undesirable. Conversely, with an organic type ultraviolet absorber content of larger than 5.0 wt %, when the polyester containing an organic type ultraviolet absorber is spun to obtain a polyester fiber, the process stability of spinning is impaired, and the clarity of the color is also reduced. Accordingly, such a content is undesirable.

As the organic type ultraviolet absorbers, there can be exemplified benzoxazine type organic ultraviolet absorber, benzophenone type organic ultraviolet absorber, benzotriazole type organic ultraviolet absorber, salicylic acid type organic ultraviolet absorber, and the like. Out of these, the benzoxazine type organic ultraviolet absorber is particularly preferable because it does not decompose at the stage of spinning. The reasons why the benzoxazine type organic ultraviolet absorber is particularly excellent as compared with the other ultraviolet absorbers are not apparent. However, mention may be made of: being high in heat resistance; less bleed-out owing to good affinity with a polyester resulting from cyclic imide esters; and other reasons.

As such benzoxazine type organic ultraviolet absorbers, there can be preferably exemplified those disclosed in JP-A-62-11744. Namely, mention may be made of 2-methyl-3,1-benzoxazin-4-one, 2-butyl-3,1-benzoxazin-4-one, 2-phenyl-3,1-benzoxazin-4-one, 2,2′-ethylenebis(3,1-benzoxazin-4-one), 2,2′-tetramethylenebis(3,1-benzoxazin-4-one), 2,2′-p-phenylenebis(3,1-benzoxazin-4-one), 1,3,5-tri(3,1-benzoxazin-4-on-2-yl)benzene, 1,3,5-tri(3,1-benzoxazin-4-on-2-yl)naphthalene, and the like.

Further, the polyester forming the antistatic core sheath type polyester ultrafine fiber of the invention preferably contains therein an inorganic type ultraviolet absorber and/or reflection agent in an amount of 0.5 wt % or less.

When the content of the inorganic ultraviolet absorber and/or reflection agent is larger than 0.5 wt %, not only the clarity is impaired, but also the knittability or weavability is impaired. Therefore, such a content is undesirable. Incidentally, as such inorganic type ultraviolet absorbers and/or reflection agents, mention may be made of inorganic compounds such as titanium dioxide, zinc oxide, alumina, magnesium oxide, talc, kaolin, calcium carbonate, and sodium carbonate.

Incidentally, into the polyester forming the antistatic core sheath type polyester ultrafine fiber of the invention, other than the organic type ultraviolet absorber, if required, a micropore forming agent, a cation mordant, a coloration inhibitor, a thermal stabilizer, a flame retardant, a fluorescent brightening agent, a colorant, an antistatic agent, a moisture absorbent, an antimicrobial agent, a minus ion generator, and the like may be added alone or two or more thereof in such a range as not to impair the objects of the invention.

Further, the area ratio of the core part polyester A and the sheath part copolymerized polyester B in a cross section orthogonal to the fiber axis is required to be set within the range of 5:95 to 80:20. When the area ratio is smaller than 5:95, expression of the antistatic performance by the polyester A becomes insufficient. In the case of larger than 80:20, when 10% or more alkali peeling is performed, the antistatic polyester at the core part dissolves. Accordingly, the antistatic performance is reduced, and the strength of the drawn yarn is reduced to 3.0 cN/dtex or less, so that the strength when formed in a cloth is insufficient. This is not suitable for applications requiring strength such as sport clothes, resulting in limited applications. Accordingly, such cases are undesirable.

For the antistatic core sheath type polyester ultrafine fiber of the invention, it is important that, by means of a conventionally known composite spinning apparatus, the foregoing copolymerized polyester B is used for the sheath side, and the polyester A is used for the core part, to be melt spun at a speed of 2000 to 3000 m/min, and to be taken up in a ratio of the discharge speed and the take-up speed for spinning (which will be hereinafter referred to as a draft ratio) within the range of 100 to 800.

As the heat treating methods, there can be adopted a method in which melt spinning is performed at the foregoing speed, and simultaneously with or subsequent to drawing, the heat treatment is carried out, or other methods, and given yarn making conditions.

Further, the resulting antistatic sheath core type polyester ultrafine fiber may be subjected to so-called DTY texturing subsequent to spinning. Alternatively, it may be drawn and once wound, and then subjected to false twist texturing.

In the invention, also preferably, a woven or knitted fabric produced from a yarn or the fiber is heat treated at a temperature of 100° C. or more. This promotes stabilization of the structure, and implementation of proper alignment by migration of the polyoxyethylene type polyether contained in the fiber, and various additives contained therein, if required. Further, if required, a relaxation heat treatment or the like can also be used in combination.

Further, if required, the woven or knitted fabric produced from the antistatic core sheath type polyester ultrafine fiber of the invention or the fiber may be subjected to appropriate hydrophilization post-processing. Further, doing so is preferable. As the hydrophilization post-processing, for example, there can be preferably adopted a method of treating with an aqueous dispersion of a polyester polyether block copolymer including terephthalic acid and/or isophthalic acid, or a lower alkyl ester thereof, and lower alkylene glycol, and polyalkylene glycol, or a method in which hydrophilic monomers such as acrylic acid and methacrylic acid are subjected to graft polymerization, and then these are converted into sodium salts.

Whereas, in the invention, in order to improve the dyeability, it is preferable that, in the polyester B, a sulfonic acid base-containing acid component has been copolymerized in an amount of 1.0 to 5.0 mol % based on the total amount of the acid components. When the amount of the sulfonic acid base-containing acid component copolymerized is less than 0.5 mol %, a sufficient dyeing performance cannot be obtained, not resulting in the one dyeable with a cation dye. When the amount exceeds 5.0 mol %, the melt viscosity of the polyester resin becomes high, undesirably incurring degradation of the spinning operability and reduction of the yarn strength.

The sulfonic acid base-containing acid component has no particular restriction so long as it is a sulfonic acid base-containing component having a functional group reacting with a polyester. Examples thereof may include 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 5-lithium sulfoisophthalic acid, sodium sulfonaphthalene dicarboxylic acid, and 5-sodium sulfoterephthalic acid. Out of these, particularly, 5-sodium sulfoisophthalic acid is favorable in color developing property by a cation dye and spinnability, and hence is preferable.

Whereas, the polyester B forming the fiber of the invention preferably contains, as a flame retardant, an organic phosphorus compound represented by the following general formula (2) so as to be 1,000 to 10,000 ppm, and preferably 3,000 to 9,000 ppm in terms of phosphorus atom content based on the total polyester weight:

[where in the formula, R₁ is hydrogen or a hydroxyalkyl group having 1 to 10 carbon atoms, R₂ is hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 24 carbon atoms, and R₃ is hydrogen, an alkyl group or a hydroxyalkyl group having 1 to 10 carbon atoms.]

Particularly, when the sulfonic acid base-containing component is contained in the polyester B, the melt viscosity is higher than that of a general polyester fiber, and hence melt dropping during burning is less likely to occur, resulting in a defect of being susceptible to spread of a fire. Therefore, the flame retardant inclusion effect is sufficiently exerted.

When the content of the organic phosphorus compound is less than 1,000 ppm in terms of phosphorus atom content, a sufficient flame retardant performance cannot be obtained. When the content exceeds 10,000 ppm, the spinning operability is reduced, or the yarn strength becomes insufficient. Thus, such a content is undesirable.

Then, an embodiment of a second invention of the present application will be described in details.

The second invention of the present application is an antistatic polyester composite false twisted textured yarn, including: two kinds of polyester filament yarns different in elongation, including bundled portions each including an alternately twisted yarn-like wrapped portion and an entangled portion, and open portions, alternately formed in the longitudinal direction therein, and characterized by satisfying the following requirements (i) to (iv):

(i) the polyester filament yarn X having a smaller elongation being a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a copolymerized polyester B, the polyester A including an antistatic polyester including, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester;

(ii) the polyester filament yarn Y having a larger elongation including a polyester containing a matting agent in an amount of 0 to 10 wt % per 100 parts by weight of an aromatic polyester;

(iii) being in a two-layer structure in which the polyester filament yarn X forms a core part of the composite false twisted yarn, and the polyester filament yarn Y wraps around the core part in an alternately twisted yarn form to form an outer layer part (sheath part); and

(iv) the mean yarn length of the polyester filament yarn Y being larger than the mean yarn length of the polyester filament yarn X by 5 to 20%,

R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1)

[where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]

The polyester filament yarn X smaller in elongation, forming the core part of the antistatic polyester composite false twisted textured yarn of the invention is a core sheath type polyester composite fiber in which the core part includes the polyester A, and the sheath part includes the copolymerized polyester B. The polyesters A and B are the same polyesters as the polyesters A and B for use in the core sheath type composite fiber of the first invention of the present application.

Then, the polyester filament yarn Y larger in elongation, forming the antistatic polyester composite false twisted textured yarn of the invention mainly embraces a polyester filament including ethylene terephthalate, trimethylene terephthalate, or tetramethylene terephthalate as a main repeating unit. However, it may be a copolymerized polyester, if required, including a third component copolymerized therein in a small amount (generally 15 mol % or less, preferably 10 mol % or less, and in particular preferably 5 mol % or less based on the total amount of the repeating units). Further, a matting agent, and other additives may also be added thereto.

Especially, when there is contained a micropore forming agent for forming micropores or microgrooves in the fiber surface or in the fiber inside by performing an alkali peeling treatment, various effects such as water absorbency, natural silk-like texture, clarity, and dry touch can be exerted according to shapes of pores or grooves. Thus, such a configuration is desirable.

As a method for obtaining the antistatic polyester composite false twisted textured yarn of the invention, mention may be made of the following: undrawn yarns of the polyester filament yarn X and the polyester filament yarn Y are simultaneously entangled, and twisted, and the resulting yarn is untwisted to form an alternately wrapped yarn.

As the combination of two or more kinds of polyester filament yarns in the invention, preferably, a yarn which can be drawn to 1.2 times or more and false twisted is used for a yarn with a smaller elongation, and a yarn which can be further elongated by 40% or more than the yarn with a smaller elongation is used for a yarn with a larger elongation.

Incidentally, properly, the elongation of the polyester filament yarn X with a smaller elongation is 50% or more, and preferably 60% or more. The elongation of the polyester filament yarn Y with a larger elongation is preferably 100% or more. Further, the difference in elongation between the low elongation polyester filament yarn X and the high elongation polyester filament yarn Y is 20% or more, preferably 40% or more, and more preferably 50% or more. It is further preferably 50 to 70%.

Herein, when the difference in elongation is less than 20%, the bulkiness of the false twisted textured yarn cannot be obtained. Thus, such a case is undesirable. Herein, adjustment of the elongations of the polyester filament yarn X and the polyester filament yarn Y can be carried out by a known method. It is preferable that the draw ratio or the like is adjusted.

Further, the proportions of the polyester filament yarn X and the polyester filament yarn Y can be appropriately selected and set according to the object. However, respective proportions are preferably 20% or more. The use ratio of both is preferably polyester yarn filament yarn X: polyester filament yarn Y=25:75 to 75:25 (weight). Particularly, the proportion of the high elongation polyester filament yarn Y with a larger elongation is preferably higher. In terms of the ratio of (polyester filament yarn X)/(polyester filament yarn Y), the range of 30/70 to 45/55 is proper.

By adopting the foregoing configuration, in the composite false twisting step, the polyester filament yarn Y is preferentially drawn. Thus, the damage to the polyester filament yarn X is less, and yarn breakage and fluffing less occur. Further, even when fluffs are formed in the polyester filament yarn X, they are covered with the polyester filament yarn Y. This reduces the problems in the subsequent cloth forming step.

Further, within such a range as not to impair the object of the invention, other fibers such as a metal-plated fiber and carbon particles-mixed fiber may be combined therein to impart the electric conductivity thereto. However, in the case of using other fibers in combination, undesirably, unless the proportion thereof is set at 30% or less of the total amount, the bulkiness tends to be reduced.

In the invention, preferably, two or more kinds of undrawn yarns having different elongations are paralleled, and are subjected to an air entanglement treatment through an air jet nozzle before drawing. As the air jet method, there can be adopted any method of a method of applying air in the direction at right angles to the running yarn, a method of applying air along the direction of advance of the running yarn, and other methods. However, the former provides a product relatively excellent in gloss, and the latter provides a product with relatively soft texture. Therefore, the method may be appropriately selected according to the object. However, in the entanglement treatment, when the overfeed ratio is set too large, a large number of loops are formed, which impairs the process stability during cloth production. Therefore, the overfeed ratio is desirably set at 10% or less.

Alternatively, a difference in overfeed ratio may be caused between undrawn yarns having different elongations. However, in this case, when a too large difference is caused, a large number of loops are formed. Therefore, generally, the same overfeed ratio is adopted.

To the false twisting apparatus, there may be applied any of a spindle for wrapping on a twist pin, a fluid type air false twisting nozzle, an inscribing type or circumscribing type friction false twisting apparatus, and a belt rubbing apparatus.

This embodiment will be described by reference to FIG. 1. Two yarns 3 and 3′ having mutually different elongations are merged at a guide 4, and then are passed through a tension adjusting device 5 and a feed roller 6. Then, the yarns are fed to an air jet nozzle for entanglement 7, and are formed into an entangled yarn having 13 or more entanglement points per meter. Then, the entangled yarn is fed to a drawing and false twisting zone by a first delivery roller 8, is passed through a heater 9 and a false twister 10, and is taken up by a second delivery roller 11. Then, the yarn is wound as a cheese 13.

Herein, after the yarn is imparted with entanglement, it is heat treated while being overfed. Then, the polyester filament yarn Y shrinks, and the polyester filament yarn X hardly shrinks or self-elongates. As a result, a difference in yarn length is caused between the polyester filament yarn X and the polyester filament yarn Y. This leads to puffiness, and the spun-like properties upon formation into a cloth.

The antistatic polyester composite false twisted textured yarn of the invention will be described by reference to the drawings. FIGS. 2A and 2B are each a side view of a false twisted textured yarn of the invention. In FIGS. 2A and 2B, I denotes an alternately twisted yarn-like wrapped portion; II, an entangled portion; and III, an open portion.

The antistatic polyester composite false twisted textured yarn of the invention essentially includes bundled portions (X) each including the alternately twisted yarn-like wrapped portion I and the entangled portion II, and the open portions (III) alternately formed as shown in FIGS. 2A and 2B in the longitudinal direction.

In the bundled portion (X) of the invention, the alternately twisted yarn-like wrapped portion I is a portion in which the core part mainly including a polyester filament yarn X is wrapped by the outer layer part mainly including a polyester filament yarn Y substantially in a bundled form. Whereas, the entangled portion (II) is a portion in which the polyester filament yarn X and the polyester filament yarn Y are closely entangled with each other in a combined formed. Below, in the invention, the (I) and the (II) are collectively referred to as the bundled portion (X).

In such a bundled portion (X), the entangled portion (II) is configured such that yarns are tight as a whole, and hence it has a large cross-sectional secondary moment. This can impart a high reboundability to the finally resulting cloth.

On the other hand, the alternately twisted yarn-like wrapped portion (I) is a portion having a puff as compared with the entangled portion (II), and can exhibit elasticity against pressing. This can impart textures such as firmness and resilience to the cloth.

In contrast, the open portion (III) adjacent to the bundled portion (X) is a portion in which the core part mainly including the polyester yarns A is covered with mainly the polyester yarns B in an individually separating and continuously inverted form in a state generally parallel to the yarn axis. This can impart spun-like bulkiness and softness which are insufficient in the bundled portion to the cloth.

The apparent single fiber fineness (the mean fineness for the one having a difference in size in the direction of length) or the total fineness as the yarn of the antistatic polyester composite false twisted textured yarn of the invention has no particular restriction. However, properly, it is within the range of 1.5 to 5.0 dtex in single fiber fineness, and 30 to 300 dtex in total fineness.

The finesses of the undrawn yarn and the partially oriented yarn should be selected according to the uses. However, in general, in terms of total fineness, it is desirable that wrapping yarn≧core yarn. Particularly preferably, the former is 30 to 40 dtex, and the latter is 20 to 150 dtex.

Whereas, the difference in yarn length between the polyester filament yarn X and the polyester filament yarn Y of the antistatic polyester composite false twisted textured yarn of the invention is preferably within the range of 5 to 20%, and more preferably 10 to 15% from the viewpoint of obtaining an excellent spunize feel.

In order to produce a cloth using the antistatic polyester composite false twisted textured yarn of the invention described up to this point, it is essential only that, if required, the yarn is subjected to proper twisting, to be woven or knitted into a desirable structure. The resulting cloth exhibits an antistatic performance unattainable with conventional woven and knitted fabrics. Further, it is possible to obtain the one having a spun-like bulkiness, soft feel and resilience of the surface, and the reboundability. Thus, this case is preferable.

Then, an embodiment of a third invention of the present application will be described in details.

A third invention of the present application is an antistatic polyester combined filament yarn including an antistatic polyester filament yarn X and a polyester filament yarn Y, and characterized by satisfying the following conditions (i) to (vi):

(i) the antistatic polyester filament yarn X being a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a copolymerized polyester B, the polyester A including an antistatic polyester containing, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester;

(ii) the single yarn fineness of the polyester filament yarn X being 1.5 dtex or less;

(iii) the friction-charged voltage of the combined filament yarn being 2000 V or less;

(iv) the combined filament yarn being the one obtained through an air entanglement step and a relaxation heat treatment step in this order;

(v) the combining ratio of the polyester filament yarn X and the polyester filament yarn Y being 8:2 to 6:4; and

(vi) the polyester filament yarn X forming an outer layer part of the combined filament yarn, and the polyester filament yarn Y forming an inner layer part thereof,

R²O—(CH₂CH₂O)_(n)(R¹⁰)_(m)—R²  (1)

[where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]

The antistatic polyester multifilament yarn X forming the polyester combined filament yarn of the invention is a core sheath type polyester composite fiber in which the core part includes the polyester A, and the sheath part includes the copolymerized polyester B. The polyesters A and B are the same polyesters as the polyesters A and B for use in the core sheath type composite fiber of the first invention of the present application.

Further, the area ratio of the polyester A and the copolymerized polyester B at the core part/sheath part in a cross section of the polyester multifilament yarn X is required to be set within the range of 5:95 to 80:20. When the area ratio is smaller than 5:95, expression of the antistatic performance by the polyester a becomes insufficient. In the case of larger than 80:20, when 10% or more alkali peeling is performed, the antistatic polyester at the core part dissolves. Accordingly, the antistatic performance is reduced, and the strength of the drawn yarn is reduced to 3.0 cN/dtex or less, so that the strength when formed in a cloth is insufficient. This is not suitable for applications requiring strength such as sport clothes, resulting in limited applications. Accordingly, such cases are undesirable.

In order to produce the polyester combined filament yarn of the invention, first, as the polyester filament yarn X′, there is adopted a polyester undrawn yarn (generally, referred to as a partially oriented yarn POY) obtained by spinning the polyesters a and b at a spinning speed as relatively high as about 2000 to 5000 m/m using a conventionally known composite spinning apparatus. Alternatively, there is used a low oriented polyester undrawn yarn spun at a spinning speed of around 1000 m/min or the one obtained by drawing a partially oriented yarn at a low ratio.

On the other hand, as the polyester filament yarn Y′, a polyester filament drawn yarn with a boiling water shrinkage of 8.0% or more is preferably used. Further preferably, a polyester filament drawn yarn with a boiling water shrinkage of 10 to 16% is used.

As such polyester filaments, there can be preferably exemplified a polyester filament drawn yarn not subjected to heat setting, and a polyester filament drawn yarn including a polyester containing, for example, isophthalic acid copolymerized therein in an amount of about 5 to 15 mol % as a third component.

The fineness of the polyester filament yarn Y is preferably 2 to 10 dtex. When it is less than 2 dtex, the strength of the combined filament yarn is reduced. When it exceeds 10 dtex, the texture becomes hard. Thus, such cases are undesirable.

FIG. 3 is a schematic front view showing one example of an apparatus for producing a combined filament yarn of the invention. A polyester filament yarn X′ which spontaneously elongates by undergoing a relaxation heat treatment and a polyester filament yarn Y′ are paralleled, and are entangled under overfeeding by an interlace nozzle 3 provided between the feed roll 1 and the first take-up roll (heat roll) 2.

With this apparatus, the first take-up roll 2 is being heated, and further, the two kinds of polyester filament yarns are overfed between the feed roll 1 and the first take-up roll 2. Therefore, the polyester filament X′ wound around the first take-up roll 2 is subjected to a relaxation heat treatment on the roll, and is allowed to spontaneously elongate. Then, by a non-contact heater 5 provided between the first take-up roll 2 and a second take-up roll 4, a second relaxation heat treatment is performed. Thus, the combined filament yarn is heat set, and is taken up into a package G.

When the two kinds of polyester filament yarns are entangled with each other, interlacing is preferably performed at 60 to 70 points per meter. To that end, it is preferable that the overfeed ratio is commonly set at 1.0 to 1.5%.

Further, as in the foregoing example, the first take-up roll 2 is heated, and a relaxation heat treatment for causing spontaneous elongation thereon is performed. This results in a compact apparatus. Thus, this is preferable. However, when the overfeed ratio (relaxation ratio) required for causing spontaneous elongation by the relaxation heat treatment is larger than the overfeed ratio suitable for entanglement at the interlace nozzle 3, the following procedure may also be adopted: another take-up roll is further provided on the downstream side of the first take-up roll 2. Thus, a prescribed relaxation heat treatment is performed between it and the take-up roll. Alternatively, when the first take-up roll 2 is taken as a heat roll, the following procedure may be adopted: the diameter on the yarn outlet side of the roll 2 is set smaller than the diameter on the yarn inlet side thereof, so that a heat treatment is performed at a prescribed overfeed ratio (relaxation ratio) on the roll.

The temperature and the overfeed ratio (relaxation ratio) of the relaxation heat treatment for causing spontaneous elongation of the polyester filament yarn X′ vary depending upon what kind of yarn is used for the polyester filament yarn X′. However, for example, when a relaxation heat treatment is performed on the first take-up roll (heat roll) 2 using a partially oriented yarn (POY) spun at a spinning speed of 3000 to 3500 m/min, preferably, the roll surface temperature is set at 100 to 130° C., and the overfeed ratio (relaxation ratio) is set at 1.0 to 1.5%.

The second-stage relaxation heat treatment by the non-contact heater 5 is a thermal fixing treatment for imparting characteristics suitable for formation into a worsted-like woven fabric with a highly reboundable wool-like touch to the combined filament yarn of the invention. It is preferable that the treatment is performed at 220° C. to 240° C. and at an overfeed ratio of 1.5 to 2.0%. The treatment time is generally 0.01 to 0.30 second. The boiling water shrinkage of the resulting polyester combined filament yarn is generally about 5 to 13%. As the non-contact heater 5, a slit heater, a pipe heater, or the like can be used.

For the combined filament yarn of the invention, preferably, the polyester filament yarn X′ which spontaneously elongates by a relaxation heat treatment and the polyester filament yarn Y′ are entangled with each other, followed by a relaxation heat treatment. As a result, while the polyester filament yarn X′ is allowed to spontaneously elongate, the polyester filament yarn Y′ is allowed to heat shrink. This prevents the yarns from coming in contact with the non-contact heater 5 during the second relaxation heat treatment. Thus, it becomes possible to produce a polyester combined filament yarn stably with reduced occurrences of yarn breakage.

The polyester filament yarn X′ is singly subjected to a relaxation heat treatment, and is allowed to spontaneously elongate. It is then thermally fixed by the second-stage relaxation heat treatment. Then, it is entangled with the polyester filament yarn Y′. Thus, a polyester combined filament yarn is produced. With this method, when the second relaxation heat treatment is performed by the non-contact heater, the yarn comes in contact with the non-contact heater, so that yarn breakage often occurs. Thus, this case is inadequate.

For the polyester combined filament yarn of the invention, preferably, the polyester filament yarn X having a single yarn fineness as ultrafine as 1.5 dtex or less, and containing an antistatic agent is situated relatively on the outer side of the combined filament yarn; the polyester filament yarn Y is situated relatively on the inner side of the combined filament yarn; and further, the combining ratio (weight ratio) of the polyester filament yarn X and the polyester filament yarn Y falls within the range of 8:2 to 5:5 by weight ratio from the viewpoints of deep color and puff. It is preferably 8 to 6:2 to 4. Within this range, touch feel, texture, softness, strength, and the like are balanced, resulting in the one having good softness, reboundability, and touch when formed in a cloth.

Further, also preferably, a woven or knitted fabric produced from the resulting combined filament yarn of the invention or the fiber is heat treated at a temperature of 100° C. or more. This promotes stabilization of the structure, and implementation of proper alignment by migration of the polyoxyethylene type polyether contained in the fiber, and various additives contained therein, if required. Further, if required, a relaxation heat treatment or the like can also be used in combination.

Further, if required, the woven or knitted fabric produced from the antistatic polyester combined filament yarn of the invention or the fiber may be subjected to appropriate hydrophilization post-processing. Further, doing so is preferable. As the hydrophilization post-processing, for example, there can be preferably adopted a method of treating with an aqueous dispersion of a polyester polyether block copolymer including terephthalic acid and/or isophthalic acid, or a lower alkyl ester thereof, and lower alkylene glycol, and polyalkylene glycol, or a method in which hydrophilic monomers such as acrylic acid and methacrylic acid are subjected to graft polymerization, and then these are converted into sodium salts.

For the antistatic property of the combined filament yarn of the invention, the friction-charged voltage is required to be 2000 V or less. When it is 2000 V or more, much static electricity is generated. As a result, unwell feeling is felt during wearing, or undesirable results are also caused in terms of safety.

Then, an embodiment of a fourth invention of the present application will be described in details.

A fourth invention of the present application is a method for producing an antistatic polyester combined filament yarn, characterized by: subjecting, an antistatic polyester filament yarn X′ having an elongation (ELA) of 80% or more, an elastic recovery at 10% elongation (ERA) of 50% or less, an elongation shear modulus (EMA) of 5.89 GPa or less, a crystallinity (XpA) of 25% or more, a boiling water shrinkage (BWSA) of 3% or less, and a thermal stress at 160° C. (TSA) of 0.44 mN/dtex or less, and satisfying the following requirements (i) and the like, to a relaxation heat treatment, then, merging it with a polyester filament yarn Y′ having an elongation (ELB) of 40% or less, an elongation shear modulus (EMB) of 7.85 GPa or more, a boiling water shrinkage (BWSB) of 5% or more, and a thermal stress at 160° C. (TSB) of 0.88 mN/dtex or more such that the weight ratio of the polyester multifilament yarn X′ and the polyester multifilament yarn Y′ is 45/55 to 70/30, and then, performing an entanglement treatment:

(i) the antistatic polyester multifilament yarn X′ being a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a copolymerized polyester B, the polyester A including an antistatic polyester containing, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester; and

(ii) the single yarn fineness of the polyester multifilament yarn X′ being 1.5 dtex or less;

R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1)

[where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]

The antistatic polyester multifilament yarn X′ forming the polyester combined filament yarn of the invention is a core sheath type polyester composite fiber in which the core part includes the polyester A, and the sheath part includes the copolymerized polyester B. The polyesters A and Bare the same polyesters as the polyesters A and B for use in the core sheath type composite fiber of the first invention of the present application.

For the antistatic polyester filament yarn X′, the elongation (ELA) is required to be 80% or more, and preferably 100 to 200%; the elastic recovery at 10% elongation (ERA) is required to be 50% or less, and preferably 40% or less; the elongation shear modulus (EMA) is required to be 5.89 GPa (600 kg/mm²) or less, and preferably 1.96 to 4.91 GPa (200 to 500 kg/mm²); the crystallinity (XpA) is required to be 25% or more, and preferably 36 to 60%; the thermal stress at 160° C. (TSA) is required to be 0.44 mN/dtex (50 mg/de) or less; and further the boiling water shrinkage (BWSA) is required to be 3% or less.

When such characteristics are shown, the antistatic polyester filament yarn X′ comes in a floating state when the combined filament yarn is heat treated. In addition, even when a load is applied in the direction of elongation, the yarn X′ does not absorb the stress, and contributes only to the improvement of the bulkiness. This resultantly inhibits the occurrence of wrinkles.

The antistatic polyester filament yarn X′ having such characteristics can be obtained in the following manner. For example, by using a conventionally known composite spinning apparatus, the polyesters a and b are molten at a temperature of 280 to 300° C., and molten and discharged through a spinneret. The cooled and solidified spun yarns are applied with an oil agent. Thus, using an interlace applying apparatus having three or more air jet holes, an air with a pressure of 0.1 to 0.3 MPa is jetted to apply interlacing. Then, the yarn is once wound on a winder via a preheat roller set at a temperature equal to or lower than the glass transition temperature of polyester and a drawing roller (preheat roller take-up speed: 1500 to 2500 m/min, draw ratio: 1.1 to 1.5).

Then, the resulting drawn yarn is subjected to heat setting at a draw ratio of 0.8 to 1.1 times (a draw ratio of 1 or less results in relaxation heat setting) through the preheat roller heated to 70 to 110° C. and the non-contact type heater set at 170 to 240° C. at a speed of 500 to 1400 m/min.

Then, for the polyester filament yarn Y′ (which may be simply referred to as a filament yarn Y′) which is the other component forming the combined filament yarn of the invention, in order to mainly absorb the load in the direction of elongation, and to hold the form stability and the stability during the post-processing step, the elongation (ELB) is required to be 40% or less, and preferably 30% or less; the elongation shear modulus (EMB) is required to be 7.85 GPa (800 kg/mm²) or more, and preferably 8.83 to 14.7 GPa (900 to 1500 kg/mm²). Whereas, in order to allow favorable bulkiness to be exhibited by a heat treatment, the boiling water shrinkage (BWSB) is required to be 5% or more, and preferably 7 to 20%. Further, in order to prevent a stress from being applied to the polyester filament yarn X′ upon heat setting by a pin tenter or the like after formation into a cloth, and to inhibit the reduction of the texture, the thermal stress at 160° C. (TSB) is required to be set at 0.88 mN/dtex (100 mg/dtex) or more, and preferably 1.76 mN/dtex (200 mg/dtex) or more.

For the filament yarn Y′ having such characteristics, for example, when the undrawn fiber including the polyester is drawn, it is essential only that the drawing temperature, the draw ratio, and the like are appropriately adjusted.

For example, the elongation and the shear modulus may be adjusted by the draw ratio, and the boiling water shrinkage may be adjusted by the heat setting conditions for drawing. Particularly, when high shrinkage is desired, non-plate drawing or the like is proper. The thermal stress can be adjusted by the draw ratio and the heating temperature during drawing, and further, the spinning speed of the undrawn fiber. However, when the spinning take-up speed is too high, the thermal stress after drawing may become unable to be increased. Therefore, it is preferable that an undrawn fiber at a spinning speed as low as 2500 m/min or less, and preferably 1700 m/min or less is drawn. Incidentally, as another method for adjusting these characteristics, there is a method in which a third component is copolymerized with the polyester. For example, copolymerization of isophthalic acid can easily provide the one having a high shrinkage characteristic.

For the combined filament yarn of the invention, the antistatic polyester filament yarn X′ is required to be relaxation heat treated, and then to be entangled and combined with the polyester filament yarn Y′. Application of thermal deformation to the yarn, such as performing of false twist crimp texturing is not preferable. With such a method, a wrinkle recovering effect becomes unable to be obtained. The reasons for this are presumed as follows. First, the heat treatment, elongation, twisting in the false twist crimp texturing, and the like change the physical properties of the polyester filament X′. Accordingly, the elongation is reduced, the thermal stress increases, and the elastic recovery is improved. This results in loss of the gradually elongating property. Whereas, when crimps are imparted to the polyester filament yarn X′, the yarn gets entangled with the adjacent yarn, or the resistance increases. Accordingly, when the yarns are formed into a cloth such as a woven fabric, the yarn shifted in the woven structure becomes less likely to return to the original position. As a result, wrinkles become more likely to occur.

Incidentally, in the case of entanglement by air jet, air may be jetted in the direction at right angles to the direction of the yarn, or along the direction of advance of the yarn. However, while the former provides a product relatively excellent in gloss, and the latter provides a product with a relatively soft texture.

Further, a difference in overfeed ratio may be caused between the polyester filament yarn X′ and the polyester filament yarn Y′ to perform air composite texturing. However, when a too large difference is caused, a large number of loops become more likely to be formed. Therefore, generally, roughly the same overfeed ratio is adopted.

The composite ratio (combining ratio) of the polyester filament yarn X′ and the polyester filament yarn Y′ is required to be 45/55 to 70/30 in terms of the weight ratio of the polyester filament yarn X′ and the polyester filament yarn Y′.

Particularly, the one in which the proportion of the polyester filament yarn X′ is higher is more likely to produce the effects of the invention. Therefore, the ratio is in particular preferably 55/45 to 70/30 in terms of the weight ratio of the polyester filament yarn X′ and the polyester filament yarn Y′. Incidentally, up to this point, description was given by taking one yarn as an example of each of the polyester filament yarn X′ and the polyester filament yarn Y′. However, it is naturally understood that these may each use two or more yarns. In short, any number of yarns may be used so long as they are fibers satisfying the physical properties which are requirements of the invention.

Further, it does not matter if a third yarn not satisfying the physical properties in accordance with the invention is added, and combined. For example, a metal-plated fiber or a carbon particles-mixed fiber may be combined therein to impart the electric conductivity thereto. However, when the proportion of such a fiber is too large, the improvement of wrinkle recoverability which is the object of the invention becomes insufficient. Therefore, the combined use ratio is desirably set at 30% at most.

Incidentally, in the antistatic core sheath type polyester fiber for use in the first invention to the fourth invention of the present application, it is preferable that there exist 3 to 8 fin parts having the protrusion coefficient defined by the following equation of 0.3 to 0.7, and protruding outwardly from the fiber cross section core part in the single fiber cross section:

protrusion coefficient=(a1−b1)/a1

where a1: the length between the center of the inscribed circle of the inner surface wall of the fiber cross section and the fin part top; and

b1: the radius of the inscribed circle of the inner surface wall of the fiber cross section (core part extrapolation inscribed circle).

The polyester multifiber of the invention having such characteristics and cross sectional shape withstands an impact imposed during draw false twist texturing. Even when drawing false twisting is carried out under general conditions, drawing can be carried out with reduced occurrences of yarn breakage (textured yarn breakage) and fluffing during draw false twist texturing. This allows the polyoxyalkylene glycol type antistatic agent to be sufficiently present in a long and narrow stripe in the direction of the fiber axis. Therefore, the antistatic property is favorable. Further, the resulting drawn false twisted textured yarn also has a fiber cross section with its fiber cross-section flatness properly dispersed in the direction of the fiber axis, and not uniform in the direction of the fiber axis. Thus, it forms a fiber aggregate with large voids between fibers. This produces effects of improving the water absorbing/quick drying performances, and the washing durability of the performances. Further, the fiber aggregate with its fiber cross-section flatness properly dispersed in the direction of the fiber axis also has the performance of providing a natural dryness in the form of a cloth in combination.

Further, the antistatic core sheath type polyester fiber is favorable in the water absorbing performance, the antistatic property, and the process stability. The reason for this is not apparent, but can be presumed as follows. To a level equal to or greater than the water absorbency like a capillary phenomenon simply due to protrusions in a specific shape, the water absorbency is improved by use as the core part antistatic agent of the hydrophilic polyoxyalkylene glycol type and ionic compounds for use as the antistatic agent. Further, the resistance between fibers is reduced during spinning drawing, particularly, during drawing. Therefore, the antistatic agent is uniformly elongated in the direction of the fiber axis. As a result, the fiber has a proper aspect ratio, and fluffing less occurs and the process stability becomes favorable.

The protrusion coefficient of the single fiber cross-sectional shape (FIG. 5 as a specific example) of the antistatic core sheath type polyester fiber is 0.3 to 0.7, and preferably 0.4 to 0.6. The fiber is required to assume a shape such that the number of the fin parts (1 of FIG. 5) protruding outward from the fiber cross-section core part is 3 to 8, and preferably 4 to 6.

The fin part having the protrusion coefficient of less than 0.3 has no function of forming a sufficient capillary void in the fiber cross section after draw false twist texturing, and cannot exhibit water absorbing/quick drying performances. Further, for such a small fin part, the anchor effect when a water absorption treatment agent is applied on the cloth is reduced. Therefore, the washing durability of the treatment agent tends to be reduced. Further, the texture of the cloth also becomes the flat and paper-like one. On the other hand, for the fin part having a protrusion coefficient of more than 0.7, the texturing tension tends to concentrate to the fin part during draw false twist texturing. Therefore, partial breakage of the fiber cross section occurs, so that the capillary cease to be formed sufficiently, resulting in insufficient water absorbing performance. Further, yarn breakage (textured yarn breakage) and fluffing during drawing false twisting step also often occur.

Incidentally, even with the fin part having a protrusion coefficient of 0.3 to 0.7, when the number of the fin parts is 1 to 2 in the single fiber cross section, only a maximum of one inwardly closed fiber cross-sectional part is formed. Accordingly, a sufficient capillary phenomenon is not exhibited, resulting in an insufficient water absorbing performance. Further, the texture of the cloth also becomes the flat and paper-like one. On the other hand, in the case of more than 8, during draw false twist texturing, the texturing tension concentration to the fin part occurs. Therefore, partial breakage of the fiber cross section occurs, so that the capillary cease to be formed sufficiently, resulting in insufficient water absorbing performance. Further, yarn breakage (textured yarn breakage) and fluffing during drawing false twisting step often occur. Incidentally, more than eight fin parts having a protrusion coefficient of less than 0.3 may be present.

The antistatic core sheath type polyester multifiber of the invention described up to this point can be formed by adjusting the discharge ports of a known core sheath composite spinning machine. However, for example, by changing the radius (a2 of FIG. 6) of the core part forming circular discharge port, the length (b2 of FIG. 6) between the central point of the circular discharge port and the tip end of the fin part forming discharge port, or the like, any given setting can be adopted so that the protrusion coefficient of the fiber cross section is 0.3 to 0.7. Further, also by changing the temperature and/or the cooling air quantity of the spin block, the protrusion coefficient of the fiber cross section can be controlled to a certain degree.

Further, each antistatic core sheath type polyester fiber for use in the first invention to the fourth invention of the present application is required to be in a flat shape in cross section orthogonal to the direction of length of the single yarn. In addition, the fiber is required to have a shape in which 3 to 6 round cross section single yarns are bonded in the longitudinal direction, and to have a constricted part at each bonding portion (see FIGS. 7A to 7H).

In the case of the shape of a general round cross section single yarn, or in which two round cross section single yarns are bonded, the core sheath type polyester flat cross section fiber in the woven fabric becomes less likely to form a widely expanding aggregate form. Thus, the void (structural void) formed by a warp and a weft becomes large. As a result, light passes through the void, which may undesirably make it impossible to obtain sufficient anti-visibility. Conversely, more than seven undesirably causes a difficulty in yarn making.

Then, the constricted part is a portion of which the length of the short side is shorter as schematically shown in FIG. 8. At such a constricted part, the depth of the concave part is preferably a depth such that the ratio B/C of the maximum value (B) and the minimum value (C) of the length of the short side is 1.05 or more (preferably 1.1 or more). Further, in FIG. 8, there is shown the one in which the concave parts are formed at both side parts. However, it is also acceptable that the concave part is formed only at one side part. Then, the number of the constricted parts is required to be two or more. When the constricted part is at one or less site, sufficient diffuse reflection of light and refraction of transmitted light cannot be obtained. Thus, undesirably, satisfactory anti-visibility cannot be obtained. The number of the constricted parts has no particular restriction so long as it is two or more. However, in consideration of the yarn-making properties, the number thereof is properly 3 to 5. Incidentally, FIG. 8 shows the case where the number of the constricted parts is two.

The antistatic core sheath type polyester fiber has a specific flat cross-sectional shape. For this reason, when it is woven, it has a closely and widely expanding structure due to the contact pressure of the woven fabric structure point. As a result, the void formed by the warp and the weft becomes small, so that the quantity of light to pass through the void decreases. In that case, a trace quantity of passing light which passes through the void undergoes diffraction. The adjacent passing light rays interfere with each other, resulting in an excellent anti-visibility effect.

Further, the cross-sectional shape of the filament is formed into a flat cross-sectional shape having a specific constricted part, and the content of the matting agent is set at a specific amount or less. Therefore, as compared with the flattened flat cross-section yarn, the round cross-section yarn, and the triangular cross-section yarn having the same fineness, diffuse reflection of light or the refraction of transmitted light which transmits through the filament increases. Accordingly, an excellent anti-visibility effect can be obtained without impairing the lighting property.

Further, the core sheath type polyester flat cross-section fiber has a widely expanding structure. For this reason, the flexural rigidity decreases, and a soft texture is also added thereto. Further, at the woven fabric structure point, the constricted part (concave part) is less likely to come in contact with other yarns. Accordingly, the friction between the warp and the weft decreases. As a result, it also becomes possible to obtain a still softer texture than that of the one having a flattened flat shape.

EXAMPLES

Below, the present invention will be described more specifically by way of Examples and Comparative Examples. However, the scope of the invention is not limited thereto at all unless it departs from the gist thereof. Incidentally, respective characteristic values in Examples were measured in the following manner.

I. Example in which the Copolymerized Polyester B is a Polyester Including an Organic Type Ultraviolet Absorbing Component Copolymerized Therein in the First Invention of the Present Application (1) Intrinsic Viscosity

A sample was dissolved in orthochlorophenol, and measurement was carried out at 35° C. using an Ubbellohde viscometer.

(2) Spun Yarn Breakage

With composite spinning equipment, melt spinning was carried out for 1 week, and the number of occurrences of yarn breakage was recorded. The number of spun yarn breakages per spindle per day is referred to as spun yarn breakage. However, yarn breakage due to the technical or mechanical factors was excluded from the number of yarn breakages.

(3) Drawn False Twisted Yarn Breakage

By means of a 216-spindle HTS-15V manufactured by Teijin Seiki (2-heater false twist texturing machine, non-contact heater specifications), draw false twist texturing was carried out continuously for 1 week. The number of yarn breakages per draw false twist texturing machine per day is referred to as drawn false twisted yarn breakage. However, yarn breakage due to the technical or mechanical factors, such as yarn breakage (knot yarn breakage) due to before or after yarn linkage, or yarn breakage upon automatic switching was excluded from the number of yarn breakages.

(4) Drawn Yarn Breakage

Draw texturing was carried out continuously for 1 week. The number of yarn breakages per drawing machine per day is referred to as Drawn false twisted yarn breakage. However, yarn breakage due to the technical or mechanical factors, such as yarn breakage (knot yarn breakage) due to before or after yarn linkage, or yarn breakage upon automatic switching was excluded from the number of yarn breakages.

(5) Birefringence Index

The birefringence index was determined from the retardation of polarized light observed on the surface of the fiber using an optical microscope and a compensator according to the ordinary method.

(6) Strength and Elongation of Yarn

Measurement was carried out according to JIS L-1013-75.

(7) Crimp Degree

A polyester false twisted textured yarn sample was applied with a tension of 0.044 cN/dtex, and wound around a hank frame to form an about 3300-dtex hank. One end of the hank was applied with two loads of 0.0177 cN/dtex and 0.177 cN/dtex, so that the length after an elapse of 1 minute S0 (cm) was measured. Then, with the load of 0.177 cN/dtex removed, the sample was treated in 100° C. boiling water for 20 minutes. After boiling water treatment, the load of 0.0177 cN/dtex was removed. Thus, the sample was air dried in a free state for 24 hours, and was applied with loads of 0.0177 cN/dtex and 0.177 cN/dtex, again. Thus, the length after an elapse of 1 minute was measured, and was referred to as S1 (cm).

Then, the load of 0.177 cN/dtex was removed, and the length after an elapse of 1 minute was measured, and was referred to as S2 (cm). The crimp degree was calculated according to the following mathematical expression, and was expressed as the mean value of 10 measurement values.

Crimp degree (%)=[(S1−S2)/S0]×100

(8) Number of Fluffs

By means of a DT-104 model fluff counter device manufactured by TORAY Industries, INC., a polyester drawn yarn sample was measured continuously for 20 minutes at a speed of 500 m/min to measure the number of fluffs formed. The number was expressed as the number per sample length of 10000 m.

(9) Texture (Softness)

Level 1: having a soft and flexible touch;

Level 2: having a little insufficient softness, but offering a reboundable feel; and

Level 3: having a dry touch feel or a hard touch feel.

(10) Chargeability Testing Method A Method (Half-Life Measuring Method)

The resulting yarn was cylindrically knitted, dyed, and humidity controlled. Then, the test piece was charged in the corona discharge field. Then, the time (in second) required for the charged voltage to attenuate to one half was measured by means of a static honest meter. A sample showing a shorter time (in second) was judged as being excellent in antistatic performance.

B Method (Friction-Charged Voltage Measuring Method)

A test piece was rubbed with a rubbing cloth while being rotated, and the resulting charged voltage is measured.

The measurement is according to L1094 chargeability testing method B method (friction-charged voltage measuring method).

As for the antistatic effect, when the friction-charged voltage is about 2000 V or less (preferably 1500 V or less), the antistatic effect is produced.

(11) Lightness Index

The lightness index L is expressed in L*a*b display system shown in JIS-Z-8729 (displaying method of an object color according to the L*a*b display system and the L*u*v* display system).

(12) Ultraviolet Transmittance

By means of a spectrophotometer MPC-3100 manufactured by Shimadzu Corp., the transmittance was measured and the ultraviolet blocking ratio at a wavelength of 380 nm was measured.

(13) Heat Retention

Under constant-temperature constant-humidity environment of a temperature of 20° C. and a humidity of 60% RH, using a 200-W reflector lamp light source as an energy source, light was applied from a height of 50 cm. Then, the temperature of the back side of the cloth after 180 seconds was measured by means of a thermocouple. When such a temperature is 30° C. or more, the sample is judged as favorable.

(Production of Polyester A)

One hundred parts of dimethyl terephthalate, 60 parts of ethylene glycol, 0.06 part of calcium acetate monohydrate (0.066 mol % based on the amount of dimethyl terephthalate), and 0.013 part of cobalt acetate tetrahydrate (0.01 mol % based on the amount of dimethyl terephthalate) as a toning agent were charged in an ester interchange reaction can. The reactants were heated from 140° C. to 220° C. over 4 hours under a nitrogen gas atmosphere. Thus, an ester interchange reaction was effected while distilling away methanol formed in the reaction can to outside the system. After completion of the ester interchange reaction, to the reaction mixture, 0.058 part of trimethyl phosphate (0.080 mol % based on the amount of dimethyl terephthalate) as a stabilizer, and 0.024 part of dimethylpolysiloxane as a defoaming agent were added. Then, after 10 minutes, to the reaction mixture, 0.041 part of antimony trioxide (0.027 mol % based on the amount of dimethyl terephthalate) was added. Simultaneously, while distilling off excessive ethylene glycol, the temperature was raised up to 240° C. Then, the reaction mixture was transferred to a polymerization reaction can. Subsequently, the pressure was reduced from 760 mmHg to 1 mmHg over 1 hour and 40 minutes, and the temperature was raised from 240° C. to 280° C. Thus, a polycondensation reaction was effected, resulting in a polyester.

Using the polyester, as an antistatic agent, (a) 4 parts of polyethylene glycol having a molecular weight of 20000 as a polyoxyalkylene type polyether, and (b) 2 parts of sodium dodecyl benzenesulfonate were added under vacuum. Further, a polycondensation reaction was effected for 240 minutes. Then, as an antioxidant, 0.4 part of IRGANOX 1010 manufactured by Ciba-Geigy Co., was added under vacuum. Then, further, a polycondensation reaction was carried out for another 30 minutes. In the polymerization reaction step, an antistatic agent was added. The resulting polymer had an intrinsic viscosity of 0.657 and a softening point of 258° C.

(Production of Polyester B)

A dry polyester containing an organic type ultraviolet absorber including 2,2′-p-phenylenebis(3,1-benzoxazin-4-one) synthesized with the method described in JP-A-62-11744, and not containing an inorganic type ultraviolet absorber such as titanium dioxide and/or a reflection agent, and having an intrinsic viscosity of 0.65 was used as the polyester B.

(Yarn Making Method)

Dry polyester A and polyester B were respectively molten with an ordinary method, and were fed to a two-component composite spinning head via a gear pump. The ratio of the core and sheath polymers was set so as to be each value described in Table 1. The simultaneously fed core part and sheath part molten polymers were cooled and solidified by cooling air from a general cross flow type spinning chimney through a spinneret having 72 circular composite spinning holes with a nozzle hole diameter of 0.25 mm, perforated therein. Thus, they were combined into one yarn while being applied with a spinning oil agent, to be taken up at a speed of 3000 m/min, resulting in a 140-dtex/72 filaments polyester undrawn yarn with a birefringence index of 0.035.

Example I-1

The polyester undrawn yarn obtained with the foregoing method was drawn to 1.8 times at a preheat roller temperature of 80° C. at a drawing speed of 600 m/min by means of a known drawing machine, followed by heat setting at a slit heater temperature of 190° C. Using the resulting drawn yarn, a cylindrical knitted fabric was produced. The antistatic property thereof was measured.

Spun yarn breakage during melt spinning occurred 3 times per day, and drawn yarn breakage occurred two times per day.

Further, the resulting drawn yarn had a single yarn fineness of 1.16 dtex, a strength of 4.8 cN/dtex, an elongation of 24%, a charged voltage of 900 V in the chargeability test B method of the cylindrical knitted fabric, an ultraviolet transmittance of 10 and an L value of 84%.

Example I-2

The polyester undrawn yarn obtained with the foregoing method was drawn to 1.8 times with a number of false twists of 2400 T/m, at a heater temperature of 210° C., and at a yarn speed, i.e., a speed of the second delivery roller 11 of 250 m/min by means of a known false twist texturing machine. Using the resulting false twisted textured yarn, a cylindrical knitted fabric was produced, and was measured for the antistatic property. The results of the process stability during melt spinning and the antistatic performance are shown in Table I-1.

Then, the woven fabric was subjected to a relaxation treatment in boiling water for 20 minutes by means of a fluid flow dyeing machine. Subsequently, a presetting treatment was carried out. Then, further, dyeing and final setting treatments were carried out, resulting in a cloth.

The resulting cloth had an antistatic performance of 15 seconds, and sensory evaluation was carried out. As a result, the cloth had very deep and high-quality feeling, and had a texture exhibiting softness.

Examples I-3 to I-6, Comparative Examples I-1 to I-7

Experiments were carried out in the same manner as in Example I-1, except that the experiments were carried out under the conditions shown in Table I-1.

The present invention particularly takes effect upon having undergone high-pressure dyeing in the post-step, and is high in heat resistance, and is practical. Further, it is suitable for sport use, and uniforms as uses thereof. Further, the portion exhibiting an antistatic property is wrapped. Thus, the antistatic portion is wrapped, and deformation is reduced, which prevents fluffing. This can be considered as the factor for keeping of the antistatic property, less fluffing during drawing, an increase in productivity, and further excellent washing durability when the fiber is formed into a woven fabric.

TABLE I-1 Example Example Example Example Example Comparative Comparative I-2 I-3 I-4 I-5 I-6 Example I-1 Example I-2 Ultraviolet absorber * % 1.0 1.0 1.0 0.5 5.0 1.0 1.0 Antistatic agent (a) % 4 4 4 4 4 4 0 Antistatic agent (b) % 2 2 2 2 2 0 2 Core sheath area ratio 30/70 30/70 30/70 30/70 30/70 30/70 30/70 Spinning speed m/min 3000 2000 4500 3000 3000 2800 2800 Drawing DR 1.8 2.4 1.4 1.8 1.8 2.0 2.0 Chargeability test A method (second) 15 30 15 15 20 75 110 B method (V) 900 1200 800 1000 1100 2800 1900 Texture softness 1 1 1 1 1 3 3 Spun yarn breakage (times/day) 3 5 7 2 4 8 98 Drawn false twisted yarn breakage 3 6 9 3 3 19 89 Textured yarn fluffs (fluffs/10⁶ m) 3 5 7 3 3 50 200 Textured yarn strength (cN/dtex) 3.8 3.4 3.8 3.9 3.2 3.5 2.3 Textured yarn elongation (%) 26 21 24 26 25 25 16 Single yarn fineness dtex 1.16 1.16 1.165 1.16 1.16 1.17 1.17 Ultraviolet transmittance % 9 10 9 15 7 13 11 L value 83 80 86 85 89 82 85 Comparative Comparative Comparative Comparative Comparative Example I-3 Example I-4 Example I-5 Example I-6 Example I-7 Ultraviolet absorber * % 1.0 1.0 1.0 — 9.0 Antistatic agent (a) % 0 4 4 4 4 Antistatic agent (b) % 0 2 2 2 2 Core sheath area ratio 0/100 30/70 30/70 30/70 30/70 Spinning speed m/min 2800 1500 5000 3000 3000 Drawing DR 2.0 2.5 1.3 1.8 1.8 Chargeability test A method (second) 300 70 78 15 15 B method (V) 5000 2100 2000 900 1000 Texture softness 3 3 3 1 1 Spun yarn breakage (times/day) 5 235 125 3 130 Drawn false twisted yarn breakage 6 432 112 3 95 Textured yarn fluffs (fluffs/10⁶ m) 15 321 548 3 250 Textured yarn strength (cN/dtex) 3.8 3.0 2.3 3.9 2.5 Textured yarn elongation (%) 28 14 15 26 26 Single yarn fineness dtex 1.16 1.16 1.16 1.16 1.16 Ultraviolet transmittance % 12 12 10 45 4 L value 81 83 84 81 86 Antistatic agent (a): polyoxyalkylene type antistatic agent Antistatic agent (b): ionic compound * Benzoxazine type organic ultraviolet absorber

II. Example in which the Copolymerized Polyester B is a Polyester Including a Phosphorus Type Flame Retardant Component Copolymerized Therein in the First Invention of the Present Application (14) Diethylene Glycol Content

Using hydrazine hydrate, a polyester composition chip is decomposed. The content of diethylene glycol in the decomposed product was measured by gas chromatography ((HP6850 model) manufactured by Hewlett Packard Co.).

(15) Phosphorus Atom Content

By means of a fluorescent X-ray spectrometer ZSX 100e model manufactured by Rigaku Co., Ltd., the content was quantitated by a fluorescent X-ray method.

(16) Flame Retardancy

According to JIS K 7201, the LOI value (limiting oxygen index) was measured, and 27 or more was judged as passed.

(17) Cation Dyeability

The resulting filament yarn was cylindrically knitted, and refining was carried out at 60° C. for 20 minutes. Then, under the following conditions, at 130° C. for 60 minutes, the sample was dyed and air dried. Then, using a compact pin tenter, heat setting was carried out at 150° C. for 1 minute. Then, a sample piece including 8 sheets stacked one on another was formed. The color tone L value of the sample piece was measured by means of a colorimeter manufactured by Macbeth Co., Ltd, and was used as the index of dyeability. A lower L value denotes that the fiber is dyed in deeper color, and 40 or less was judged as passed.

Dye AIZEN COLOR CATION BLUE 0.2% owf Leveling agent acetic acid 0.3 g/L sodium sulfate 3.0 g/L

Example II-1 Production of Polyester A

Polyester B was produced in the same manner as with the method for producing the polyester B in Example in which the copolymerized polyester B is a polyester including an organic type ultraviolet absorbing component copolymerized therein in the first invention of the present application.

Production of Polyester B

To a mixture of 100 parts by mass of dimethyl terephthalate and 50 parts by mass of ethylene glycol, 3.0 parts by mass of an organic phosphorus compound represented by the following formula (2) was added as a flame retardant. Thus, the ester interchange reaction was terminated.

[R₁ is a 2-hydroxyethyl group, R₂ is a methyl group, and R₃ is hydrogen.]

Thereafter, to the reaction product, 0.018 part by mass of antimony trioxide was added. The mixture was transferred to a reaction vessel equipped with a stirrer, a nitrogen inlet port, a pressure reducing port, and a distiller. The temperature was raised up to 280° C., and a polycondensation reaction was effected in vacuum as high as 30 Pa or less. This resulted in a polyester having an intrinsic viscosity of 0.58 dL/g, and a diethylene glycol content of 2.46 mass %. The content of phosphorus was 4700 ppm.

(Yarn Making)

The sheath part polyester B and dry core part polyester A were respectively molten with an ordinary method, and were fed to a two-component composite spinning head via a gear pump. The ratio of the core and sheath polymers was set so as to be each value described in Table 1. The simultaneously fed core part and sheath part molten polymers were cooled and solidified by cooling air from a general cross flow type spinning chimney through a spinneret having 72 circular composite spinning holes with a nozzle hole diameter of 0.25 mm, perforated therein. Thus, they were combined into one yarn while being applied with a spinning oil agent, to be taken up at a speed of 3000 m/min, resulting in a 140-dtex/72 filaments polyester undrawn yarn with a birefringence index of 0.035. The resulting yarn was drawn to 1.8 times with a known drawing method, resulting in a yarn of the invention (single yarn fineness 1.1 dtex).

Using the resulting yarn, a cylindrical knitted fabric was produced, and was measured for the antistatic property. Then, the fabric was subjected to a relaxation treatment in boiling water for 20 minutes. Subsequently, a presetting treatment was carried out. Then, further, dyeing and final setting treatments were carried out, resulting in a cloth including a polyester composite drawn yarn.

The resulting cloth had a friction-charged voltage of 900 V, and a flame retardancy of 28. Sensory evaluation was carried out. As a result, the cloth had very clear and deep, and high-quality feel, and had a texture exhibiting softness.

Comparative Example II-1

Experiments were carried out in the same manner as in Example II-1, except that a flame retardant was not used.

The resulting cloth had a friction-charged voltage of 900 V. Sensory evaluation was carried out. As a result, the cloth had very deep, and high-quality feel, and had a texture exhibiting softness. However, the flame retardancy was 21.

Comparative Example II-2

Experiments were carried out in the same manner as in Example II-1, except that an antistatic agent was not used.

Sensory evaluation of the resulting cloth was carried out. As a result, the cloth had very clear and deep, and high-quality feel, and had a texture exhibiting softness. The flame retardancy was 28, and good. However, the friction-charged voltage was 5000 V, so that crackling static electricity was generated during wearing.

Comparative Example II-3

Experiments were carried out in the same manner as in Example II-1, except that an organic sulfonic acid metal salt was not used.

The resulting cloth had a friction-charged voltage of 900 V, and a flame retardancy of 28. However, sensory evaluation was carried out. As a result, the cloth had no dyed clarity, and was not so good.

III. Example in which the Cross-Sectional Shape of the Antistatic Core Sheath Type Polyester Fiber is Modified in the First Invention in the Present Application (18) Light Transmittance

According to JIS L10556.1 A method (illuminance 100000 lx), the light blocking ratio (%) was measured. Then, the light transmittance (%) was determined by the following equation. 20% or more was judged as passed.

(Light transmittance)=100−(Light blocking ratio)

(19) Anti-Visibility

As the measuring method in the daytime, under environment of indoor 80-W fluorescent lamp of 700 lx, a recognized object is placed at a position 20 cm away from an anti-visible woven fabric. An evaluator was situated at a position 30 cm away from the woven fabric outside the room (daytime sunlight 100000 lx) across the woven fabric. Thus, it was visually determined whether or not the evaluator could recognize the recognized object. Criteria are as follows: the case where the recognized object can be recognized is rated as AAAA; the case where the recognized object can be slightly recognized is rated as AA; the case where the contour of the recognized object is visible is rated as BB; and the case where the recognized object could not be recognized is rated as CC.

Whereas, as the measuring method in the nighttime, under environment of indoor 80-W fluorescent lamp of 700 lx, a recognized object is placed at a position 20 cm away from an anti-visible woven fabric. An evaluator was situated at a position 30 cm away from the woven fabric outside the room (nighttime 0.21 lx) across the woven fabric. Thus, it was visually determined whether or not the evaluator could recognize the recognized object. Criteria are set as the same as with the measuring method in the daytime.

(20) Constricted Part Ratio and Flatness Coefficient (See FIG. 8)

Constricted part ratio: The single yarn of the flat cross-section yarn of the invention was sampled at 10 sites each every 10 m in the fiber axis direction. The microphotograph of each cross section was taken. For all the fiber cross section photographed, the ratio (B/C) of the maximum length B of the minor axis to the minimum length C of the minor axis of the constricted part was measured. The mean value of all the measurement values is taken as the constricted part ratio.

Flatness coefficient: The single yarn of the flat cross-section yarn of the invention was sampled at 10 sites each every 10 m in the fiber axis direction. The microphotograph of each cross section was taken. For all the fiber cross section photographed, the ratio (A/B) of the length (A) of the major axis, i.e., the longest site to the maximum length (B) of the minor axis C orthogonal to the major axis was measured. The mean value of all the measurement values is taken as the flatness coefficient.

Example III-1 Production of Polyester A

Polyester A was produced in the same manner as with the method for producing the polyester A in Example in which the copolymerized polyester B is a polyester including an organic type ultraviolet absorbing component copolymerized therein in the first invention of the present application.

Production of Polyester B

Polyester B was produced in the same manner as with the method for producing the polyester B in Example in which the copolymerized polyester B is a polyester including an organic type ultraviolet absorbing component copolymerized therein in the first invention of the present application.

(Yarn Making)

Yarn making was carried out in the following manner. Dry polymers were respectively molten with an ordinary method in spinning equipment, and were fed to a two-component composite spinning head via a gear pump. The ratio of the core and sheath polymers was set so as to be 30/70. The simultaneously fed core part and sheath part molten polymers were spun out at a spinning temperature of 300° C. through a spinneret perforated in a four-crested flat cross section (3 constricted parts), and cooled and solidified by cooling air from a general cross flow type spinning chimney. Thus, they were combined into one yarn while being applied with a spinning oil agent, to be taken up at a speed of 4000 m/min. The resulting yarn was subsequently drawn to 1.3 times without once being wound, resulting in a core sheath type polyester flat cross-section fiber of 84 dtex/36 fil with a flat cross section (B/C=1.2, cross-section flatness 3.2) having 3 constricted parts in cross-sectional shape of the filament.

The resulting yarn had a strength of 4.5 cN/dtex and a friction-charged voltage (B method) of 900 V. The cross-sectional shape of the resulting single yarn is shown in FIG. 7( e).

Then, the core sheath type polyester flat cross-section fiber was used in an untwisted form in an amount of 100% for a warp and a weft, thereby to form a plain woven fabric with a cover factor of 1000 by an ordinary weaving method. Ordinary dyeing processing is performed, resulting in an anti-visible woven fabric of the invention.

For the anti-visible cloth, the light transmittance was 35%, the anti-visibility (daytime) was rated as AAAA, and the anti-visibility (nighttime) was rated as AA.

Example III-2

Experiments were carried out in the same manner as in Example 1, except that the cover factor of the anti-visible woven fabric was changed to 880 in Example III-1. Then, weaving/dyeing processing were performed, resulting in an anti-visible woven fabric.

For the anti-visible cloth, the pollen removable rate was 97%, the light transmittance was 40%, the anti-visibility (daytime) was rated as AA, and the anti-visibility (nighttime) was rated as AA.

Example III-3

Experiments were carried out in the same manner as in Example 1, except that the cover factor of the anti-visible woven fabric was changed to 1800 in Example III-1. Then, weaving/dyeing processing were performed, resulting in an anti-visible woven fabric. For the anti-visible cloth, the pollen removable rate was 98%, the light transmittance was 25%, the anti-visibility (daytime) was rated as AAAA, and the anti-visibility (nighttime) was rated as AA.

Example III-4

Experiments were carried out in the same manner as in Example 1, except that as the multifilament (A), the 200 T/m twisted one was used in Example III-1. Then, weaving/dyeing processing were performed, resulting in an anti-visible woven fabric. For the anti-visible cloth, the pollen removable rate was 98%, the light transmittance was 33%, the anti-visibility (daytime) was rated as AA, and the anti-visibility (nighttime) was rated as AA.

Example III-5

Experiments were carried out in the same manner, except that the number of the constricted parts was five in Example III-1. The cross-sectional shape of the resulting single yarn is shown in FIG. 7( g). For the anti-visible cloth, the pollen removable rate was 99%, the light transmittance was 34%, the anti-visibility (daytime) was rated as AAAA, and the anti-visibility (nighttime) was rated as AA.

Comparative Example III-1

Experiments were carried out in the same manner as in Example 1, except that the cross-sectional shape of the filament was changed into a flattened flat cross section (flatness coefficient A/B=3.2) without a constricted part in Example III-1. This resulted in an anti-visible woven fabric. The fiber strength was 5.0 cN/dtex, and the friction-charged voltage was 900 V. For the anti-visible cloth, the pollen removable rate was 98%, the light transmittance was 30%, the anti-visibility (daytime) was rated as BB, and the anti-visibility (nighttime) was rated as BB.

Comparative Example III-2

Experiments were carried out in the same manner as in Example 1, except that the cross-sectional shape of the filament was changed into FIG. 7( h) in Example III-1. This resulted in an anti-visible woven fabric. Fluffing largely occurred in the yarn making step, and the productivity was bad. Accordingly, it was not possible to form a woven fabric.

Comparative Example III-3

Experiments were carried out in the same manner as in Example 1, except that the cross-sectional shape of the filament was changed into a round cross section of FIG. 7( b) in Example III-1. This resulted in an anti-visible woven fabric. The fiber strength was 6.0 cN/dtex, and the friction-charged voltage was 900 V. For the anti-visible cloth, the pollen removable rate was 98%, the light transmittance was 30%, the anti-visibility (daytime) was rated as CC, and the anti-visibility (nighttime) was rated as CC.

Comparative Example III-4

Experiments were carried out in the same manner, except that an antistatic agent was not added to the polyester A in Example III-1. This resulted in an anti-visible woven fabric. The fiber strength was 5.0 cN/dtex, and the friction-charged voltage was 900 V. For the anti-visible cloth, the pollen removable rate was 15%, the light transmittance was 35%, the anti-visibility (daytime) was rated as AAAA, and the anti-visibility (nighttime) was rated as AA.

Comparative Example III-5

Experiments were carried out in the same manner, except that the polyester A was allowed to contain titanium oxide (KA-30, SAKAI CHEMICAL INDUSTRY, Co., Ltd.) in an amount of 1.0 wt % in Example III-1. This resulted in an anti-visible woven fabric. The fiber strength was 4.0 cN/dtex, and the friction-charged voltage was 900 V. For the anti-visible cloth, the pollen removable rate was 98%, the light transmittance was 10%, the anti-visibility (daytime) was rated as BB, and the anti-visibility (nighttime) was rated as BB.

Comparative Example III-6

Experiments were carried out in the same manner as in Example 1, except that the cover factor of the anti-visible woven fabric was changed to 2500 in Example III-1. Then, weaving/dyeing processing were performed, resulting in an anti-visible woven fabric. For the anti-visible cloth, the pollen removable rate was 98%, the light transmittance was 15%, the anti-visibility (daytime) was rated as AA, and the anti-visibility (nighttime) was rated as AA.

Comparative Example III-7

Experiments were carried out in the same manner as in Example 1, except that the cover factor of the anti-visible woven fabric was changed to 600 in Example III-1. Then, weaving/dyeing processing were performed, resulting in an anti-visible woven fabric. For the anti-visible cloth, the pollen removable rate was 98%, the light transmittance was 15%, the anti-visibility (daytime) was rated as CC, and the anti-visibility (nighttime) was rated as CC.

IV. Example in which the Antistatic Core Sheath Type Polyester Fiber has a Modified Cross Sectional Shape, and has Been Subjected False Twisting Texturing in the First Invention of the Present Application (21) Boiling Water Shrinkage

By a sizing reel with a frame circumference of 1.125 m, a 20-wound hank was formed, and was applied with a load of 0.022 cN/dtex. Thus, it was hung on a scale plate, to measure the initial hank length L0. Then, the hank was treated in a 65° C. warm water bath for 30 minutes, and then, it was allowed to cool. Again, it was hung on the scale plate, to measure the length L after shrinkage. Then, the boiling water shrinkage was calculated according to the following equation:

Boiling water shrinkage=(L0−L)/L0×100(%)

(22) Protrusion Coefficient

A microphotograph of the cross section of polyester multifiber was taken. Thus, the length (a1) between the center of the inscribed circle of the inner surface wall of the single fiber cross section and the fin part top; and the radius (b1) of the inscribed circle of the inner surface wall of the fiber cross section were measured. Then, the protrusion coefficient was calculated according to the following equation:

protrusion coefficient=(a1−b1)/a1

(23) Water Absorbing and Quick Drying Properties (Wicking Value)

As the index of the water absorbing/quick drying performance, according to JIS L1907 water absorption testing method of fiber product, Section 5.1.1 water absorption speed (dropping method), the number of seconds (wicking value) until dropped water droplets cease to surface reflect from the surface of a test fabric including a polyester false twisted textured yarn was adopted. Incidentally, L10 represents the wicking value (second) after performing washing 10 times according to JIS L0844-A-2 method.

(24) Textured Yarn Breakage Ratio

By means of an SDS-8 model draw false twist texturing machine manufactured by Scragg Ltd., a 10-kg wound polyester multifiber package is subjected to draw false twist texturing, to form two 5-kg wound polyester false twisted textured yarn packages. When the machine was operated in this manner, the number of yarn breakages was recorded, and the textured yarn breakage ratio was calculated according to the following equation.

Textured yarn breakage ratio=number of breakages/(number of working spindles×2)×100

Examples IV-1 to IV-3, Comparative Examples IV-1 to IV-2 Production of Polyester A

Polyester A was produced in the same manner as with the method for producing the polyester A in Example in which the copolymerized polyester B is a polyester including an organic type ultraviolet absorbing component copolymerized therein in the first invention of the present application.

Production of Polyester B

Polyester B was produced in the same manner as with the method for producing the polyester B in Example in which the copolymerized polyester B is a polyester including an organic type ultraviolet absorbing component copolymerized therein in the first invention of the present application.

(Yarn Making)

Yarn making was carried out in the following manner. Dry polymers were respectively molten with an ordinary method in spinning equipment, and were fed to a two-component composite spinning head via a gear pump. The ratio of the core and sheath polymers was set so as to be each value shown in Table IV-1.

The simultaneously fed core part and sheath part molten polymers were spun out each through a spinneret including 24 groups of discharge port groups each having four fin part forming discharge ports with a slit width of 0.10 mm and a length (b2 of FIG. 5) between the central point of the discharge port and the tip end of 0.88 mm, and having a core part forming circular discharge port radius [a2 of FIG. 5] of 0.15 mm, perforated therein. Each spun yarn was cooled and solidified by cooling air from a general cross flow type spinning chimney. Thus, they were combined into one yarn while being applied with a spinning oil agent, to be taken up at a speed of 3000 m/min. This resulted in a polyester undrawn yarn of 140 dtex/24 filaments.

The polyethylene terephthalate multifiber was mounted on an SDS-8 model draw false twist machine (3-axis friction disk false twisting unit, 216 spindles) manufactured by Scragg Ltd. Thus, draw false twist texturing was carried out at a draw ratio of 1.65, a heater temperature of 175° C., a number of twisting of 3300 times/m, and a drawing false twisting speed of 600 m/min. This resulted in a polyethylene terephthalate drawn false twisted textured yarn with a fineness of 84 dtex.

The results of the chargeability test wicking values (L0 and L10), the textured yarn breakage ratio, and textured fluff in Examples IV-1 to IV-3, and Comparative Examples IV-1 to IV-2 are summarized and shown in Table IV-1.

Comparative Example IV-3

Experiments were carried out in the same manner as in Example IV-1, using the polyester B including no antistatic agent added therein as the polyester A.

Comparative Example IV-4

In Example IV-1, the spinneret was changed to a general spinneret [spinneret for round cross-section) having 24 groups of 0.3-mm circular discharge port groups perforated therein. Thus, the polymers were cooled/solidified by cooling air from a general cross flow type spinning chimney, and were combined into one yarn while being applied with a spinning oil agent, to be taken up at a speed of 3000 m/min, resulting in a polyester undrawn yarn of 140-dtex/24 filaments.

The subsequent draw false twist texturing and the like were carried out in the same manner as in Example IV-1.

Comparative Example IV-5

Only the polyester B including no antistatic agent added therein was used, and was cooled/solidified by cooling air from a general cross flow type spinning chimney, through a general spinneret [spinneret for round cross-section) having 24 groups of 0.3-mm circular discharge port groups perforated therein. Thus, the polyester was combined into one yarn while being applied with a spinning oil agent, to be taken up at a speed of 3000 m/min, resulting in a polyester undrawn yarn of 140 dtex/24 filaments.

The subsequent draw false twist texturing and the like were carried out in the same manner as in Example IV-1.

TABLE IV-1 Example Example Example Comparative Comparative Comparative Comparative Comparative Item IV-1 IV-2 IV-3 Example IV-1 Example IV-2 Example IV-3 Example IV-4 Example IV-5 Fiber cross-sectional shape FIG. 1 FIG. 1 FIG. 1 FIG. 1 FIG. 1 FIG. 1 Round Round Anti-static agent (a) % 4 6 4 0.08 40 0 4 0 Anti-static agent (b) % 2 3 2 0.04 20 0 2 0 Core sheath area ratio 30/70 30/70 20/80 50/50 20/80 30/70 30/70 — Protrusion coefficient 0.5 0.5 0.5 0.5 0.5 0.4 1 1 Number of fins 4 4 4 4 4 4 0 0 Chargeability test A 15 12 15 38 8 48 20 56 method (second) B method (V) 1100 750 1400 3900 600 4800 1600 5700 Water absorbing quick 6 7 6 6 6 15 48 32 drying property (wicking) Spun yarn breakage 3 5 7 3 35 4 3 1 (times/day) Textured yarn breakage 5 7 10 4 76 5 15 2 (times/day) Textured yarn fluffs 5 10 11 14 200 10 70 2 (fluffs/10⁶ m) Antistatic agent (a): polyoxyalkylene type antistatic agent Antistatic agent (b): ionic compound

V. Example of a Second Invention of the Present Application (27) Bulkiness Evaluation

Evaluation of bulkiness was carried out according to the following measuring method. Namely, a composite mottled yarn was wound 120 times around a sizing reel (circumferential length 1.125 m) to form a hank. At one end of a sample obtained by folding this in half, a load having a weight 3 times the weight of the hank was hung. Thus, the sample was heat treated by 195° C. hot air for 5 minutes, and then cooled. Then, the yarn was charged in a box (height 2.5 cm, width 1.0 cm, length 10 cm, bottom with a radius of curvature of 0.5 cm), and loaded with a lid (weight three times that of the hank). The bulkiness was calculated from the volume (V cm³) at that step, and the weight (W g) of the hank (combined filament yarn) according to the following equation:

Bulkiness (cm³/g)=V/W

When this value is 50 or more, the bulkiness is rated as “good”. When this value is less than 50, the bulkiness is rated as “bad”.

(28) Texture Evaluation: Combination of Flexibility, Dryness, and Spunize Appearance

Respective evaluation items for the texture were ranked on a three-point scale as follows. By the sensory evaluation by five skilled panelists, the one judged by all the panelists as very good is expressed as (AA); the one judged by three or more panelists as good is expressed as (BB); and the one judged by three or more panelists as bad is expressed as (CC).

(28) Difference in Yarn Length: Calculated According to the Following Equation

Difference in yarn length (%)=(L _(s) −L _(c))/L _(c)×100

(where L_(s) and L_(c) represent the mean values of respective total single fiber yarn lengths of the polyester yarn A and the polyester yarn B included in a 5-cm piece cut at a given site of the combined filament yarn.)

Example V-1 Production of Polyester A

Polyester A was produced in the same manner as with the method for producing the polyester A in Example in which the copolymerized polyester B is a polyester including an organic type ultraviolet absorbing component copolymerized therein in the first invention of the present application.

Production of Polyester B

Polyester B was produced in the same manner as with the method for producing the polyester B in Example in which the copolymerized polyester B is a polyester including an organic type ultraviolet absorbing component copolymerized therein in the first invention of the present application.

(Yarn Making of Polyester Filament Yarn X)

Yarn making was carried out in the following manner. In spinning equipment, dry polymers were respectively molten with an ordinary method, and were fed to a two-component composite spinning head via a gear pump. The ratio of the core component and sheath component polymers formed as described above was set so as to be each value described in Table 1. The simultaneously fed core component and sheath component molten polymers were cooled and solidified by cooling air from a general cross flow type spinning chimney through a spinneret having 36 circular composite spinning holes with a nozzle hole diameter of 0.25 mm, perforated therein. Thus, they were combined into one yarn while being applied with a spinning oil agent, to be taken up at a speed of 3000 m/min, resulting in an undrawn polyester multifilament of 120-dtex/36 filaments. The resulting yarn characteristics are as shown in Table 1.

(Yarn Making of Polyester Filament Yarn Y)

On the other hand, polyethylene terephthalate with an intrinsic viscosity of 0.64 was molten and discharged through a spinneret. The discharged yarn was cooled and solidified, and then, was applied with an oil agent, to be taken up at a speed of 1000 m/min, resulting in a partially oriented undrawn polyester filament yarn of 150-dtex/48 filaments.

The resulting undrawn polyester filament yarn and a partially oriented polyester filament yarn were respectively disentangled, and paralleled. Thus, in the step of FIG. 1, an entanglement treatment and draw false twist texturing were carried out.

Namely, the two yarns were fed to the feed roller 6, and subjected to an interlace treatment between it and the first delivery roller 8 at an overfeed ratio of 3.0% and under a compressed air pressure of 0.25 MPa by the interlace nozzle 7. Thus, the yarn was applied with 60 entanglement points per meter. Subsequently, the entangled yarn was fed to a false twisting zone via the roller 8, and was wound on a winder at a draw ratio of 1.5 times, a heater temperature of 450° C., and a yarn speed of 550 m/min. This resulted in a false twisted textured yarn of 190 dtex/84 filaments.

The resulting false twisted textured yarn was observed under a microscope. As a result, the yarn was found to mainly have the structure [structure including the alternately twisted yarn-like wrapped portion I—the entangled portion II,—the open portion (III) in this order] shown in FIGS. 2A and 2B.

The resulting yarn was used for a warp and a weft, which were woven into Habutae. With ordinary methods, refining, heat setting, and dyeing were performed, resulting in a plain dyed woven fabric. The evaluation results are shown in Table 1.

Comparative Examples V-1 to V-5

Experiments were carried out in the same manner as in Example V-1, except that the amount of each antistatic agent to be used was changed to each condition shown in Table 1. The evaluation results are shown in Table V-1.

TABLE V-1 Polyester yarn X Antistatic Polyester False twisted textured yarn agent Core/ yarn Y Antistatic Crimp Difference weight (%) sheath Elongation Elongation Bulkiness performance Fluffing Strength degree in yarn a) b) ratio (%) (%) cm³/g (V) frequency cN/dtex (%) length (%) Texture Example V-1 4 2 30/70 68 121 55 900 AA 3.8 6 13 AA Comparative 4 0 30/70 47 92 43 2800 AA 4.0 7 11 AA Example V-1 Comparative 0 2 30/70 180 200 18 1900 CC 3.0 8 5 CC Example V-2 Comparative 0 0 30/70 68 90 20 5000 AA 4.5 5 8 AA Example V-3 Comparative 4 2 30/70 105 121 15 900 AA 3.5 6 6 CC Example V-4 Comparative 4 2 100/0  70 120 52 900 CC 2.0 7 10 AA Example V-5

VI. Example of Third Invention of the Present Application (29) Texture of Cloth

The combined filament yarn was woven into a plain woven fabric of 60 warps/cm and 35 wefts/cm. The texture thereof after dyeing was evaluated.

(Softness)

Level 1: having a soft and flexible touch;

Level 2: having a little insufficient softness, but offering a reboundable feel; and

Level 3: having a dry touch feel or a hard touch feel.

Example VI-1 Production of Polyester A

Polyester A was produced in the same manner as with the method for producing the polyester A in Example in which the copolymerized polyester B is a polyester including an organic type ultraviolet absorbing component copolymerized therein in the first invention of the present application.

Production of Polyester B

Polyester B was produced in the same manner as with the method for producing the polyester B in Example in which the copolymerized polyester B is a polyester including an organic type ultraviolet absorbing component copolymerized therein in the first invention of the present application.

(Yarn Making)

Yarn making was carried out in the following manner. Dry polymers were respectively molten with an ordinary method in spinning equipment, and were fed to a two-component composite spinning head via a gear pump. The ratio of the core and sheath polymers was set so that core part/sheath part=30/70. The simultaneously fed core part and sheath part molten polymers were cooled and solidified by cooling air from a general cross flow type spinning chimney through a spinneret having 72 circular composite spinning holes with a nozzle hole diameter of 0.25 mm, perforated therein. Thus, they were combined into one yarn while being applied with a spinning oil agent, to be taken up at a speed of 3000 m/min. This resulted in a polyester partially oriented yarn (POY) of 90 dtex/72 filaments (single fiber fineness: 1.25 dtex) (polyester multifilament yarn X′).

On the other hand, polyethylene terephthalate isophthalate copolymerized polyester (10.0 mol % isophthalic acid copolymerized) with an intrinsic viscosity of 0.64 was molten at 280° C., and spun at a spinning speed of 1450 m/min, resulting in an undrawn yarn. The resulting undrawn yarn was drawn to 2.9 times at 87° C., resulting in a heat shrinkable polyester yarn (heat shrinkable polyester multifilament yarn Y′) with a boiling water shrinkage of 15%, and of 55 dtex/12 filaments (single fiber fineness: 4.6 dtex).

The polyester multifilament yarn X′ and the heat shrinkable polyester multifilament yarn Y′ were used, thereby to produce a polyester combined filament yarn by means of the apparatus shown in FIG. 3.

Namely, both the polyester multifilament yarns X′ and Y′ were paralleled to be fed to the interlace nozzle 3 provided between the feed roll 1 and the first take-up roll (heat roll with a surface temperature of 120° C.) 2 at a speed of 600 m/min, and an overfeed ratio of 1.2%. Thus, the yarns were entangled by 2.0 kg/cm² compressed air, to apply 65 points/m interlacing. Incidentally, the combining ratio of the polyester multifilament yarn X′ and the polyester multifilament yarn Y′ was 62:38.

Then, still at an overfeed ratio of 1.2%, the yarn was wound around the heat roll 2 with a surface temperature of 120° C. 8 times, and subjected to a relation heat treatment. Thus, the polyester multifilament yarn X′ was allowed to spontaneously elongate, and at the same time, the polyester multifilament Y′ was heat shrunk. Then, by the slit heater 5 provided between the heat roll 2 and the second take-up roll 4, the yarns were subjected to a second relaxation heat treatment at 230° C. and an overfeed ratio of 1.8% for 0.05 second to perform heat setting, and wound two times around the second take-up roll (cool roll) 4. Then, the yarn was taken up in the package 6 as a combined filament yarn of 150 dtex/84 filaments.

For the chargeability of the resulting combined filament yarn, the friction-charged voltage was 900 V.

During production of the polyester combined filament yarn, no contact of the yarn with the slit heater 5 was observed. Yarn breakage occurred only one time per day per spindle.

The resulting combined filament yarn was woven into a plain woven fabric of 60 warps/cm and 35 wefts/cm. The fabric was dyed with an ordinary method at 135° C. for 60 minutes to be dyed in black. The resulting dyed woven fabric had a texture of level 1, and had a highly reboundable wool-like touch, and was a worsted-like woven fabric having puffiness, and caused no crackling static electricity during wearing.

Comparative Example VI-1

Experiments were carried out in the same manner, except that the single yarn fineness of the polyester multifilament yarn X was set at 3.0 dtex in Example VI-1. The resulting dyed woven fabric was hard in texture, and not good in touch feel (Level 3).

Comparative Example VI-2

Experiments were carried out in the same manner, except that the combining ratio of the polyester multifilament yarn X and the polyester multifilament yarn Y was set at 50:50 in Example VI-1. The resulting dyed woven fabric was good in antistatic property, but hard in texture, and thus was not good (Level 3).

Comparative Example VI-3

Experiments were carried out in the same manner, except that the combining ratio of the polyester multifilament yarn X and the polyester multifilament yarn Y was set at 90:10 in Example VI-1. The resulting dyed woven fabric was good in antistatic property. However, it less shrunk during the relaxation heat treatment, so that the polyester multifilament Y was not covered with the polyester multifilament X sufficiently. The fabric thus was not good in touch feel (Level 1).

Comparative Example VI-4

Experiments were carried out in the same manner, except that an antistatic agent was not added to the polyester multifilament yarn X in Example VI-1. The woven fabric using the resulting combined filament yarn had a texture of level 1, and was good in puffiness and high reboundability. However, it had no antistatic property, and hence it caused crackling static electricity during wearing.

Comparative Example VI-5

Experiments were carried out in the same manner, except that the amount of polyoxyalkylene type polyether to be added was set at 0.1 part in Example VI-1.

The woven fabric using the resulting combined filament yarn had a texture of level 1, and was good in puffiness and high reboundability. However, it had no antistatic property, and hence it caused crackling static electricity during wearing.

Comparative Example VI-6

In Example VI-1, the relaxation heat treatment was not carried out, and a combined filament yarn was formed with a general false twisting step. The resulting one often underwent yarn breakage and fluffing, and was bad in yield.

VII. Example of a Fourth Invention of the Present Application (30) Elastic Recovery at 10% Elongation (ER)

According to JIS L 1013, the test length of a sample was set at 25 cm. Thus, both ends thereof were held and fixed by an air chuck with the initial load imposed thereon at 1/30 g per denier. As the measurement conditions, after 10% elongation at a tensile rate of 20%/min, the sample was returned to the initial load point while removing the load at a return rate of 20%/min. The measurement was carried out 3 times, and the mean value thereof was determined.

Elastic recovery at 10% elongation=(elongation at 10% elongation−residual elongation)/elongation at 10%−elongationt×100

(31) Elongation Shear Modulus (EM)

Measurements are carried out using a constant rate elongation tensile tester and a recording device interlocked therewith. The test length of a sample was set at 25 cm. Thus, both ends thereof were held and fixed by an air chuck with the initial load imposed thereon at 1/30 g per denier. The measurement condition was set as a tensile rate of 20%/min. A tangent line is drawn at the most inclined curve portion by the initial load elongation curve to read the stress at 100% elongation. The measurement was carried out 5 times, and the mean value thereof was determined.

Elongation shear modulus (EM)=9×100×stress (g) at 1% elongation×sample specific gravity/fineness (denier)

(32) Thermal Stress (TS) (at 160° C.)

Measurements are carried out using a thermal stress measuring unit, and a recording device interlocked therewith. A sample is formed into a 5-cm loop using a sampling jig. Then, the thermal stress measuring unit and the recording device were prepared in a state such as to be capable of measuring a stress within the range of 0 to 20 g at 20° C. to 300° C. The previously sampled 5-cm sample loop is hung on the upper and lower hooks of the thermal stress measuring unit, and is applied with an initial load of 1/30 g per denier. Then, the measurement of the thermal stress is started. The measurement is carried out at a heating rate of 300° C./120 seconds. Upon heating to 300° C., the measurement is completed. The measurement is carried out 3 times. For the thermal stress (160° C.), a stress g at 160° C. point was read, and was converted into a stress per 1 dtex.

Example VII-1 Production of Polyester A

Polyester A was produced in the same manner as with the method for producing the polyester A in Example in which the copolymerized polyester B is a polyester including an organic type ultraviolet absorbing component copolymerized therein in the first invention of the present application.

Production of Polyester B

Polyester B was produced in the same manner as with the method for producing the polyester B in Example in which the copolymerized polyester B is a polyester including an organic type ultraviolet absorbing component copolymerized therein in the first invention of the present application.

(Production of Polyester Multifilament Yarn X)

Yarn making was carried out in the following manner. Dry polymers were respectively molten with an ordinary method in spinning equipment, and were fed to a two-component composite spinning head via a gear pump. The ratio of the core and sheath polymers was set so as to be each value shown in Table 1. The simultaneously fed core part and sheath part molten polymers were cooled and solidified by cooling air from a general cross flow type spinning chimney, through a spinneret having 72 circular composite spinning holes with a nozzle hole diameter of 0.25 mm, perforated therein. Thus, they were combined into one yarn while being applied with a spinning oil agent, to be taken up at a speed of 3000 m/min. This resulted in a core sheath type polyester undrawn yarn of 90 dtex/72 filaments (single yarn fineness 1.25 dtex), with a birefringence index of 0.035.

The elongation (ELA) was 120%; the elastic recovery at 10% elongation (ERA), 30%; the elongation shear modulus (EMA), 3.92 GPa (400 kg/mm²); the crystallinity (XpA), 40%; the boiling water shrinkage (BWSA), 1%; and the thermal stress at 160° C. (TSA), 0.26 mN/dtex (30 mg/dtex).

(Production of Polyester MultiFilament Yarn Y)

On the other hand, polyethylene terephthalate with an intrinsic viscosity of 0.64 (measured in a 35° C. orthochlorophenol solution), including 10 mol % isophthalic acid copolymerized therein was molten and discharged through a spinneret. The discharged yarn was cooled and solidified, and then, was applied with an oil agent, to be taken up at a speed of 1200 m/min once. Then, drawing was carried out at a preheat roller temperature of 85° C., a heat set heater (contact type) temperature of 170° C., a draw ratio of 3.1 times, and a drawing speed of 1200 m/min, resulting in a polyester multifiber B (single yarn fineness 4.6 dtex) of 55 dtex/12 filaments. The polyester multifiber B had an elongation (ELB) of 30%, an elongation shear modulus (EMB) of 11.77 GPa (1200 kg/mm²), a boiling water shrinkage (BWSA) of 17%, and a thermal stress at 160° C. (TSB) of 4.4 mN/dtex.

(Production of Combined Filament Yarn)

The antistatic polyester multifilament yarn X was subjected to a relaxation heat treatment at a preheat roller temperature of 110° C., a heat set heater (non-contact type) temperature of 230° C., a relaxation ratio of 2%, and a speed of 600 m/min. Then, it was merged with the polyester multifilament yarn Y, and combined and entangled with each other by means of an air entanglement nozzle, resulting in a composite yarn. The yarn was wound on a winder, resulting in a combined filament yarn of 150 dtex/84 filaments. The single yarn fineness of the antistatic polyester multifiber A was 1.2 dtex.

The resulting combined filament yarn was used for a warp and a weft, which were woven into Habutae. With ordinary methods, refining, heat setting, and dyeing were performed, resulting in a plain dyed woven fabric. The evaluation results are shown in Table 3.

Incidentally, respective evaluation items for the texture were ranked on a three-point scale as follows. By the sensory evaluation by five skilled panelists, the one judged by all the panelists as very good is expressed as 1; the one judged by three or more panelists as good is expressed as 2; and the one judged by three or more panelists as bad is expressed as 3.

Further, as the evaluation of the wrinkle recovery, a woven fabric was inserted in a tube form into the instrument as in FIG. 4, and a weight was put thereon. Thus, the fabric was allowed to stand for 3 hours. Then, the weight was removed, and the fabric was allowed to stand for 30 minutes. The degree of wrinkling at this step was scored on criteria of Table VII-1.

Examples VII-2 and Comparative Examples VII-1 to VII-4

Experiments were carried out in the same manner as in Example VII-1, except that the experiments were carried out under the conditions shown in Table VII-2.

TABLE VII-1 State of woven fabric Class No wrinkles are left without doing anything 5 Wrinkles are left, but are smoothed out when stretched 4 Wrinkles are left loosely even when stretched 3 Wrinkles are considerably left even when stretched 2 Wrinkles cannot be smoothed out at all, and are sharply 1 left

TABLE VII-2 Comparative Comparative Comparative Comparative Example VII-1 Example VII-2 Example VII-1 Example VII-2 Example VII-3 Example VII-4 Fiber X Fiber Y Fiber X Fiber Y Fiber X Fiber Y Fiber X Fiber Y Fiber X Fiber Y Fiber X Fiber Y Antistatic agent (a) % 4 — 4 — 4 — 0 — 4 — 4 — Antistatic agent (b) % 2 — 2 — 0 — 2 — 2 — 2 — Core sheath area ratio 30/70 0/100 30/70 0/100 30/70 0/100 30/70 0/100 30/70 0/100 30/70 0/100 ELA 120 30 115 30 110 30 125 30 120 30 120 30 ERA 30 80 28 80 35 80 30 80 30 80 30 80 EMA 3.92 11.77 4.0 11.77 3.9 11.77 3.85 11.77 3.92 11.77 3.92 11.77 TSA 0.26 4.4 0.28 4.4 0.25 4.4 0.26 4.4 0.26 4.4 0.26 4.4 Mixing ratio 55 45 60 40 55 45 55 40 10 90 80 20 Single yarn fineness dtex 1.25 4.6 1.25 4.6 1.25 4.6 1.25 4.6 1.25 4.6 1.25 4.6 antistatic property B method (V) 900 900 2800 2500 900 900 Wrinkle recovery 4 to 5 4 to 5 4 to 5 4 to 5 1 to 2 4 to 5 Texture softness  1  1   1   1  3 2 to 3 Static electricity during wearing None None Occurred Occurred None None 

1. An antistatic core sheath type polyester ultrafine fiber, being a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a copolymerized polyester B, characterized by satisfying the following requirements: (i) the single yarn fineness being 1.5 dtex or less; (ii) the ratio A:B of the area A of the core part and the area B of the sheath part being within the range of 5:95 to 80:20; (iii) the single yarn strength being 3.0 cN/dtex or more; (iv) the friction-charged voltage of the yarn being 2000 V or less; and (v) the polyester A being an antistatic polyester comprising, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester; R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1) [where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]
 2. The antistatic core sheath type polyester ultrafine fiber according to claim 1, wherein the copolymerized polyester B is a polyester comprising an organic type ultraviolet absorbing component copolymerized therein in an amount of 0.1 to 5.0 wt % based on the total weight of the polyester.
 3. The antistatic core sheath type polyester ultrafine fiber according to claim 2, wherein the organic type ultraviolet absorbing component is a benzoxazine type organic ultraviolet absorber.
 4. The antistatic core sheath type polyester ultrafine fiber according to claim 1, wherein the copolymerized polyester B is a polyester comprising an organic sulfonic acid metal salt copolymerized therein in an amount of 1.0 to 5.0 mol % based on the total amount of acid components except for the organic sulfonic acid metal salt.
 5. The antistatic core sheath type polyester ultrafine fiber according to claim 1, wherein the copolymerized polyester B is a polyester comprising a phosphorus type flame retardant component represented by the following general formula (2) in an amount of 1,000 to 10,000 ppm in terms of phosphorus atom based on the total weight of the polyester:

[where in the formula, R₁ is hydrogen or a hydroxyalkyl group having 1 to 10 carbon atoms, R₂ is hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 24 carbon atoms, and R₃ is hydrogen, an alkyl group or a hydroxyalkyl group having 1 to 10 carbon atoms.]
 6. The antistatic core sheath type polyester ultrafine fiber according to claim 1, the core sheath type polyester composite fiber having 3 to 8 fin parts in a shape protruding outwardly from the fiber cross section central part in a cross section orthogonal to the direction of length of the single yarn, and the protrusion coefficient of the fin parts defined by the following equation being 0.3 to 0.7: protrusion coefficient=(a1−b1)/a1 where a1: the length between the center of the inscribed circle of the inner surface wall of the cross section orthogonal to the fiber axis and the fin part top; and b1: the radius of the inscribed circle of the inner surface wall of the cross section orthogonal to the fiber axis.
 7. The antistatic core sheath type polyester ultrafine fiber according to claim 1, the core sheath type polyester composite fiber having a flat shape including 3 to 6 round cross section single yarns bonded to one another in the longitudinal direction in a cross section orthogonal to the direction of length of the single yarn, and the flatness α/β expressed as the ratio of the maximum diameter α (major axis) of the flat shape and the length β of the maximum diameter (minor axis) orthogonal to the major axis being 3 to
 6. 8. A cloth characterized by including the antistatic core sheath type polyester ultrafine fiber according to claim
 1. 9. An antistatic polyester composite false twisted textured yarn, comprising: two kinds of polyester filament yarns different in elongation, including bundled portions each including an alternately twisted yarn-like wrapped portion and an entangled portion, and open portions, alternately formed in the longitudinal direction therein, and characterized by satisfying the following requirements (i) to (iv): (i) the polyester filament yarn X having a smaller elongation being a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a copolymerized polyester B, the polyester A comprising an antistatic polyester comprising, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester; (ii) the polyester filament yarn Y having a larger elongation comprising a polyester containing a matting agent in an amount of 0 to 10 wt % per 100 parts by weight of an aromatic polyester; (iii) being in a two-layer structure in which the polyester filament yarn X forms a core part of the composite false twisted yarn, and the polyester filament yarn Y wraps around the core part in an alternately twisted yarn form to form an outer layer part (sheath part); and (iv) the mean yarn length of the polyester filament yarn Y being larger than the mean yarn length of the polyester filament yarn X by 5 to 20%, R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1) [where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]
 10. The antistatic polyester composite false twisted textured yarn according to claim 9, satisfying the following conditions (i) to (v): (i) the friction-charged voltage of the antistatic polyester composite false twisted textured yarn being 2000 V or less; (ii) the ratio of the core part area and the sheath part area in a cross section orthogonal to the fiber axis of the polyester yarn X being within the range of 5:95 to 80:20; (iii) the strength of the antistatic polyester composite false twisted textured yarn being 1.5 cN/dtex or more; and (iv) the crimp degree of the antistatic polyester composite false twisted textured yarn being 2 to 8%.
 11. The antistatic polyester composite false twisted textured yarn according to claim 9, the core sheath type polyester composite fiber having 3 to 8 fin parts in a shape protruding outwardly from the fiber cross section central part in a cross section orthogonal to the direction of length of the single yarn, and the protrusion coefficient of the fin parts defined by the following equation being 0.3 to 0.7: protrusion coefficient=(a1−b1)/a1 where a1: the length between the center of the inscribed circle of the inner surface wall of the cross section orthogonal to the fiber axis and the fin part top; and b1: the radius of the inscribed circle of the inner surface wall of the cross section orthogonal to the fiber axis.
 12. The antistatic polyester composite false twisted textured yarn according to claim 9, the core sheath type polyester composite fiber having a flat shape including 3 to 6 round cross section single yarns bonded to one another in the longitudinal direction in a cross section orthogonal to the direction of length of the single yarn, and the flatness α/β expressed as the ratio of the maximum diameter α (major axis) of the flat shape and the length β of the maximum diameter (minor axis) orthogonal to the major axis being 3 to
 6. 13. A cloth characterized by including the antistatic polyester composite false twisted textured yarn according to claim
 9. 14. An antistatic polyester combined filament yarn comprising an antistatic polyester filament yarn X and a polyester filament yarn Y, and characterized by satisfying the following conditions (i) to (vi): (i) the antistatic polyester filament yarn X being a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a polyester B, the polyester A comprising an antistatic polyester containing, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester; (ii) the single yarn fineness of the polyester filament yarn X being 1.5 dtex or less; (iii) the friction-charged voltage of the combined filament yarn being 2000 V or less; (iv) the combined filament yarn being the one obtained through an air entanglement step and a relaxation heat treatment step in this order; (v) the combining ratio of the polyester filament yarn X and the polyester filament yarn Y being 8:2 to 6:4; and (vi) the polyester filament yarn X forming an outer layer part of the combined filament yarn, and the polyester filament yarn Y forming an inner layer part thereof, R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1) [where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]
 15. The antistatic polyester combined filament yarn according to claim 14, the core sheath type polyester composite fiber having 3 to 8 fin parts in a shape protruding outwardly from the fiber cross section central part in a cross section orthogonal to the direction of length of the single yarn, and the protrusion coefficient of the fin parts defined by the following equation being 0.3 to 0.7: protrusion coefficient=(a1−b1)/a1 where a1: the length between the center of the inscribed circle of the inner surface wall of the cross section orthogonal to the fiber axis and the fin part top; and b1: the radius of the inscribed circle of the inner surface wall of the cross section orthogonal to the fiber axis.
 16. The antistatic polyester combined filament yarn according to claim 14, the core sheath type polyester composite fiber having a flat shape including 3 to 6 round cross section single yarns bonded to one another in the longitudinal direction in a cross section orthogonal to the direction of length of the single yarn, and the flatness α/β expressed as the ratio of the maximum diameter α (major axis) of the flat shape and the length β of the maximum diameter (minor axis) orthogonal to the major axis being 3 to
 6. 17. A cloth characterized by including the antistatic polyester combined filament yarn according to claim
 14. 18. A method for producing an antistatic polyester combined filament yarn, characterized by: subjecting, an antistatic polyester filament yarn X′ having an elongation (ELA) of 80% or more, an elastic recovery at 10% elongation (ERA) of 50% or less, an elongation shear modulus (EMA) of 5.89 GPa or less, a crystallinity (XpA) of 25% or more, a boiling water shrinkage (BWSA) of 3% or less, and a thermal stress at 160° C. (TSA) of 0.44 mN/dtex or less, and satisfying the requirements of the following (i) and the like, to a relaxation heat treatment, then, merging it with a polyester filament yarn Y′ having an elongation (ELB) of 40% or less, an elongation shear modulus (EMB) of 7.85 GPa or more, a boiling water shrinkage (BWSB) of 5% or more, and a thermal stress at 160° C. (TSB) of 0.88 mN/dtex or more such that the weight ratio of the polyester multifilament yarn X′ and the polyester multifilament yarn Y′ is 45/55 to 70/30, and then, performing an entanglement treatment: (i) the antistatic polyester multifilament yarn X′ being a core sheath type polyester composite fiber having a core part including a polyester A, and a sheath part including a copolymerized polyester B, the polyester A comprising an antistatic polyester containing, as an antistatic agent, (a) a polyoxyalkylene type polyether represented by the following general formula (1) in an amount of 0.2 to 30 parts by weight, and (b) an organic ionic compound substantially nonreactive with the polyester in an amount of 0.05 to 10 parts by weight per 100 parts by weight of an aromatic polyester; and (ii) the single yarn fineness of the polyester multifilament yarn X′ being 1.5 dtex or less; R²O—(CH₂CH₂O)_(n)(R¹O)_(m)—R²  (1) [where in the formula, R¹ is an alkylene group or a substituted alkylene group having two or more carbon atoms, R² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 40 carbon atoms, a monovalent hydroxyhydrocarbon having 2 to 40 carbon atoms, or a monovalent acyl group having 2 to 40 carbon atoms, n is an integer of 1 or more, and m is an integer of 1 or more.]
 19. The method for producing an antistatic polyester combined filament yarn according to claim 18, the core sheath type polyester composite fiber having 3 to 8 fin parts in a shape protruding outwardly from the fiber cross section central part in a cross section orthogonal to the direction of length of the single yarn, and the protrusion coefficient of the fin parts defined by the following equation being 0.3 to 0.7: protrusion coefficient=(a1−b1)/a1 where a1: the length between the center of the inscribed circle of the inner surface wall of the cross section orthogonal to the fiber axis and the fin part top; and b1: the radius of the inscribed circle of the inner surface wall of the cross section orthogonal to the fiber axis.
 20. The method for producing an antistatic polyester combined filament yarn according to claim 18, the core sheath type polyester composite fiber having a flat shape including 3 to 6 round cross section single yarns bonded to one another in the longitudinal direction in a cross section orthogonal to the direction of length of the single yarn, and the flatness α/β expressed as the ratio of the maximum diameter α (major axis) of the flat shape and the length β of the maximum diameter (minor axis) orthogonal to the major axis being 3 to
 6. 21. A cloth characterized by including the antistatic polyester combined filament yarn produced by the method for producing an antistatic polyester combined filament yarn according to claim
 18. 